discern between and
discern between (someone or something) and (someone or something)
To recognize the differences between people or things. I have a hard time discerning between Jim and Greg, but they are identical twins after all. You can discern between hydrangea and phlox by looking at their leaves.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
discern between someone or something and someone or something
to detect the difference between people and things. I cannot discern between the dark trees and the dark sky behind them. I cannot discern between the person and the background.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.