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.
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.