OBL Kapoor, godbrother of Srila Prabhupada, explains how the various sampradayas view simultaneous oneness with, and difference from, God, in this chapter of his well-known book. Srila Prabhupada especially liked this book and wanted ISKCON centers to distribute it. This chapter makes the concepts of oneness and difference very clear and as understandable as anything “inconceivable” can ever be!
This chapter is helpful for those are practitioners of bhakti-yoga, for those who teach bhakti, for scholars, and anyone who is spiritually curious.
Here’s the book chapter as a pdf: View PDF
Here are some other links on this topic:
Brief definition of simultaneous oneness & difference