know chalk from cheese

know chalk from cheese

To be able to tell two things apart (especially by recognizing their differences). Of course I know which twin is which, I know chalk from cheese, after all! Leah has a beauty mark under her left eye, and Deena doesn't.
See also: chalk, cheese, know
Farlex Dictionary of Idioms.
See also:
  • know a hawk from a handsaw
  • as we know it
  • I know
  • before you know where you are
  • by any chance
  • AFAIK
  • closed book, a
  • a closed book
  • before you know it
  • (I) can't say as I do