Alc 109b τοῦτο γε διαφέρει ὅλον τε καὶ πᾶν

τοῦτο γε διαφέρει ὅλον τε καὶ πᾶν.
the commentary says it is a cliché meaning ‘a world of difference.’ I wanted to check it in dictionaries but could not find it.