Hare Krishna to all,I have a query. All four authenticated sampradayas are authenticated, originated with pure devotees of Lord. But although they are talking about the same supreme personality of Godhead, yet they have some dissimilarities. Why their are some differences like:1. Sri Sampradaya (Ramanujacharya Sampradaya)Philosophy: Vishishtadvaita ("Qualified Monoism"), RamanujacharyaOriginal Personality of Godhead - Lord Vishnu (not Lord Krishna).2. Brahma sampradaya ( Madhvacharya sampradaya)Philosophies: Dvaita ("dualism")Original Personality of Godhead - Lord Krishna.3. Rudra sampradaya (Vallabhacharya sampradaya)Philosophy: Shuddhadvaita ("pure nondualism")Original Personality of Godhead - Lord Krishna.4. Kumara-sampradaya (Nimbarka sampradaya)Philosophy: Dvaitadvaita ("duality in unity")Original Personality of Godhead - Lord Krishna.Ques 1: Why there are so much basic differences?Ques 2: Does it means that no one can realize God completely. Even such great devotees also?Ques 3: Which among them has best philosophical knowledge and why?