Questions : Why are worshipers of Krishna called Vaishnava, why not Krishnavas? Does this not indicate that we are actually worshippers of Vishnu?
Answer by Romapada Swami:
Vishnu is non-different from Krishna, and there is no material distinction between Vishnu and Krishna. When we speak of a distinction between Vishnu and Krishna in terms of Who is the source, this does not indicate some kind of material discrimination where one is superior to another. Just as in the example of many candles being lit from one original candle, there is factually no fundamental difference.
When we speak of Vishnu tattva, it refers to the Supreme Energetic Personality of Godhead, as distinct from His subordinate energies viz., shakti tattva or jiva tattva. Krishna and all His plenary expansions discussed in the above question belong to Vishnu tattva. So, yes, devotees of Krishna are worshipers of Vishnu and so they are Vaishnavas.
In the spiritual world, everything is absolute yet there are differences, varieties and varying degrees of intimacy with the Lord. Generally by the term Vishnu we refer to the plenary expansions in the Vaikuntha region or the purusha avataras in the material region to refer to the majestic (aisvarya) feature of the Lord, whereas worshipers of Krishna are more attracted to His sweetness (madhurya) feature since in the feature of Krishna there is the greatest degree of intimacy and sweetness of exchange of love between the Lord and His devotees.