判若黑白　

◎ 判若黑白 pànruòhēibái

[the difference is as between the black and the white] 像黑的與白的那樣明顯區(qū)分。形容界限分明

夫文之高下雅俗,判若黑白。——清· 方望溪《書祭裴太常文后》