From Longman Dictionary of Contemporary Englishchalk and cheesechalk and cheeseBritish EnglishDIFFERENT completely different from each other The two brothers are as different as chalk and cheese. They’re like chalk and cheese, those two. → chalk
Examples from the Corpus
chalk and cheese• We are chalk and cheese; our personalities are radically different and likely to abrade each other.• The two men are as different as chalk and cheese.• They are psychologically, spiritually and in personality as different as chalk and cheese.• This twin thing ... you are separate people, different as chalk and cheese.• They know that to compare that game to next Sunday's contest is to compare chalk and cheese.• Middlesbrough and East Cleveland are like chalk and cheese. 