Annamaacharya, the great Vaak-geya-kaaraka of Aandhra Pradesh, in one of his divya sankeertana "Enta maatramuna evvaru talichina '." says:
How much ever one imagines that much only are You:
For Vaishnavas You are Vishnu
For Vedaantas You are Parabrahma
For Shaivas and other bhaktas You are Shiva
For Kaapaalikas You are Kaala-Bhairava
For Shaakteyaas You are Shakti
For people with alpa-buddhi You appear as alpam
For people who know Your Garima and have Ghana-buddhi You are a Ghana
For people who are Sharanaagati You are Venkateshvara
Harihara is the name of a combined deity form of both Vishnu (Hari) and Shiva (Hara) from the Hindu tradition. Also known as Shankaranarayana ("Shankara" is Shiva, and "Narayana" is Vishnu), Harihara is thus worshipped by both Vaishnavites and Shaivities as a form of the Supreme God, as well as being a figure of worship for other Hindu traditions in general. Harihara is also sometimes used as a philosophical term to denote the unity of Vishnu and Shiva as different aspects of the same Supreme God. The exact nature of both Vishnu and Shiva (from their associated stories in Vedic and Puranic scriptures), and their position of difference or unity (or both), is a subject of some debate amongst the different philosophical schools.
Different Concepts:
Due to the fluid and diverse nature of Hinduism there are a wide variety of beliefs and traditions associated with both Vishnu and Shiva. Some schools hold that only Vishnu (including his associated avatars) is the Supreme God, and others that Shiva (including his different incarnations) is actually the Supreme being. Some argue that both Shiva and Vishnu are the Supreme God - both being different aspects of the one person; and there are others still who regard the Supreme God as being ultimately formless (advaita, no material form) and thus see both Vishnu and Shiva as different facets of the one formless Brahman, with no material form.
Depending on which scriptures (and translations) are quoted, evidence is available to support each of the different arguments. In most cases, even if one personality is taken as being superior over the other, much respect is still offered to both Vishnu and Shiva by the other's worshippers (i.e. Shiva is still regarded as being above the level of an ordinary jiva and 'the greatest of the Vaishnavas' by Vaishnavas who worship only Vishnu).
One and the same:
Sivananda states: "Shiva and Vishnu are one and the same entity. They are essentially one and the same. They are the names given to the different aspects of the all-pervading Supreme Soul or the Absolute. 'Sivasya hridayam vishnur-vishnoscha hridayam sivah'Vishnu is the heart of Siva and likewise Siva is the heart of Vishnu'."
Swaminarayan holds that Vishnu and Shiva are different aspects of the same God.
Depiction in art:
Harihara is depicted in art as split down the middle, one half representing Shiva, the other half representing Vishnu. The Shiva half will have the matted locks of a yogic master piled high on his head and sometimes will wear a tiger skin, reserved for the most revered ascetics. Shiva's pale skin may be read as ash-covered in his role as an ascetic. The Vishnu half will wear a tall crown and other jewelry, representing his responsibility for maintaining world order. Vishnu's black/blueish skin represents holiness. Broadly, these distinctions serve to represent the duality of humble religious influence in the ascetic and authoritative secular power in the king or householder. However, in other aspects Shiva also takes on the authoritative position of householder, a position which is directly at odds with the ascetic position depicted in his Harihara manifestation.
Source: Wikipedia
Story of Shiva and Vishnu
Source: Moral Stories
"There are two mahaa-phala daayaka Vrukshas. One by the name Vaasudeva and the other by the name Vaamadeva. They differ only in their sumas (flowers) ('su' is replaced by 'ma' in their names), but both give the same phalas (fruits, which is moksham)". It is also often said, "How much one does not see the difference between Shiva and Vishnu, that much his aayu will increase".
One day, when Lakshmi and Vishnu were together in vihaaram, Lakshmi sees Ucchaishravam, her brother, the horse of Revanta who is the son of Surya. Engrossed in seeing her brother, she does not reply to the repeated calls of Vishnu. Seeing her attraction, Vishnu gives her shaapam to go to Bhulokam in the form of a horse and come back to Vaikuntam only after getting a son equal to Himself! She comes to Bhuloka to experience the shaapam and realizing that none other than her brother, Shiva can help her calm Vishnu, she immediately does a tapas for Him and Shiva appears to save her soodari. Lakshmi says "You and Vishnu are both same, the Paramaatma. Please help me!". Shiva says "Soodari! How do you know that we both are same? All learned people know that. Who told you?". Lakshmi says, "Once Mahavishnu Himself told me this. Seeing Him in deep Daiva-dhyaanam, I asked Him "During Samudramanthanam, I thought you were the greatest of all and hence chose you. Devaadideva! Who is better than you that you are in dhyaanam of Him?". Mahavishnu replied "I am doing Shankara-dhyaanam. He is Eshwara. He is the same as Me. All learned people know that. If someone is my devotee but still hates Shiva, he will fall into naraka".
Saying this, She asks Shiva to pursuade Vishnu to bless Her with a child. Shiva sends Chitrarupa as a duta to convince Vishnu. Vishnu immediately accepts and comes to Bhuloka and blesses Lakshmi with Ekaveera, who is equal to Vishnu Himself. From Ekaveera came forth the Haihaya dynasty, of which the most noted king is Kartavirya Arjuna (Ekaveera's grandson).
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Once when Naarada, the avatar of Vishnu, recited prayers glorifying Lord Shiva as the supreme controller of the universe, Lord Shiva, the best of Vaishnavas, at once covered his ears and angrily replied, "I am not the Lord of the universe, nor an object of Krishna's mercy! I am just a poor aatma always hankering for the favor of the servants of His servants." (Thus in this small story, Naarada, avataar of Vishnu, glorifies Shiva as the Paramaatma and Shiva glorifies Vishnu as the Paramaatma!)
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The story of Hanuman, who is the 11th avataar of Shiva and Raama, the purna avataar of Vishnu also reveals the same. Both of them acheived great tasks:
1. Restricting the great samudram, Raama along with His entire army crossed the satpa-samudras! Hanuman, in one small jump, crossed it!
2. In the greatest, unparalleled ghora-yuddham, which was never seen before or will ever be seen, Raama killed Raavana! Hanuman killed Mairaavana, who was many times stronger than Raavana, with great ease!
3. Raama melted a stone, with the touch of His lotus feet, for Ahalya! Hanuman melted a stone with His sweet Gandharva gaanam!
Also to note: Krishna lifted Govardhana giri, balanced on his little finger and saved the lives of Gopaalas! Hanuman brought the Sanjeevani Parvatam from Himaalayas to Lanka and saved Lakshmana!
Though they did great tasks like this, always Hanuman worshipped Raama, with great Vinayam(humility) and Raama worshipped Shiva with unparalleled devotion.
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Impressed by the great tapas of Vi?h?u for Paramasiva, Siva gave Vi?h?u the Sudarshana Cakram.
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Once Shri Krishna, the avataar of Mahaavishnu, came to Upamanyu maharshi, when he was at Himaalayas. Shri Krishna said "Upamanyu muniindra! You are the greatest in the Shiva Bhaktas. I came here to do Tapas of Paramashiva to get santaanam. Please teach Me Shaiva-vidhi and vidhaanam".
Upamanyu replied "O Shri Krishna! I know who You are. Shiva puuja is not new to You. Though You know it, to make everybody know, I will tell You '" Saying thus, Upamanyu told Shri Krishna how to do Shiva-aaraadhana.
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This happened after the episode of Naarada, coming under Vishnu maaya, gives shaapam to Vishnu: (This is one of the reasons of Shri Raama avatar) Naarada says "Svaami! Please forgive Me. I, coming under influence of Your maaya, got ahankaar and did Your ninda. Please tell Me what can save Me from this ghora-paapam".
Vishnu says: "O Priya Naarada! You go and do paaraayana of Shankara Shatanaamams. Then You will get Shaanti. Shiva is whom I respect the most. Even by mistake don't forget this. One who doesnt have Shiva-anugraham cannot be My Bhakta. Believe this'then My maaya wont affect you."
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Once Vyaasa Bhagavaan came under the influence of Shiva-maaya and started telling in his Pravachanams that Vishnu is greater than Shiva. Once Nandeeshvara also heard Vyaasa Bhagavaan saying this. Vishnu Murti then appeared before Veda Vyaasa and told Him "O Maharshi! Dont you know that I and Shiva are the same? Knowing this why are you telling like this in your pravachanams?" Veda Vyaasa then had great pashchaattaapam and asked Kshama from Nandeeshvara.
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The phalam(fruit) of Vishnu Pooja is Shiva Bhakti ' the example is that of Arjuna. Arjuna ofcourse was the greatest Shri Krishna Bhakta. But it was Shiva who gave Arjuna moksham, when Arjuna was born as Bhakta Kannappa, in the great Kaalahastsi Kshetram.
Similarly the phalam of Shiva Pooja is Shri Raama Bhakti ' the examples are stories of Kaaka Bhushundi and Valmiki Maharshi. Kaaka Bhushundi was a great Shiva Bhakta and hence Shiva grants him Raama Bhakti Saamraajyam. Valmiki did tapas for Shiva using the Panchaakshari mantram given to him by the great Saptarshis and as a result became the Aadi Kavi and wrote the great Raamaayanam.
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Raasleela
It was the day when the "punya-vruksham" of Gopikas delivered its ripe fruits, called Moksham. It was the day when the Aaraadhana of Gopikas was blessed by Lord Krishna. Gopikas realized Shri Krishna, the Sarvaantaryaami, everywhere. As a result of their Aaraadhana-bhakti they realized the paramaatma's poorna-svaroopam with each one of them. Who could miss watching the Raasaleela, where the Lord showered His Karuna-jyotsna ? All the Brahma-aadi devatas were present.
Parama Shiva, the greatest bhakta of Shri Krishna, was also present in the form of a Gopika. Shri Krishna, who is always in nirantara-shiva-dhyaanam, searched for Parameshvara. Finally He realized that Shiva is none other than one of the Gopikas having sampoorna aanandam of dancing with Him. Shri Krishna paramaatma then does stuti of Eshvara and asks to bless them by staying there at Vrundaavanam by the name of Gopeeshvara.
Even today we can visit Lord Shiva, in the form of Gopeeshvara, at Vrindaavan.
Lord Shiva is the most devoted Vaishnava, according to Srimad Bhagavatham. There it is mentioned: "vaishnava:nam yadha: sambhuh".
He is also one of the 12 Mahajanas (Bhagavata Purana lists twelve Mahajanas, great devotees of Vishnu and knowers of Dharma. They are Lord Brahma, Narada, Shiva, the four Kumaras, Kapila - the son of Devahuti, Svayambhuva Manu, Prahlada, Janaka, Bhishma, Bali, Suka, and Yama.).
If one prays to Lord Shiva with genuine devotion undoubtedly they would end up at Krishna Bhakti.
Ramesvara Mahadeva
When Sri Ramacandra was making the bridge to Lanka, he established a Siva-linga (deity form of Siva) called Ramesvara. All the common people began glorifying Lord Siva, shouting, "Ramesvara ki jaya! You are Rama's isvara: you are the lord of Rama." The demigods were unsatisfied by this and announced through an arial voice, "Ramas ca asau isvarah: Rama is God, and Sankara is also God; they are the same." Hearing this, the Siva-linga broke. Lord Siva emerged from the linga and told them all, "You are all foolish; you do not know my tattva, the established truths regarding my identity. Rama is my beloved and my God, and that is why I am called Ramesvara."
