different as chalk and cheese

English

Some cheeses look superficially like chalk.

Chalk may have a similar surface, but unlike cheese is hard.

Etymology

Attested in variant form 1393. The surface of some cheeses, particularly unaged ones, looks similar to chalk – white, crumbling – but in substance cheese is soft, while chalk is hard.

Adjective

different as chalk and cheese (not comparable)

1. (UK, simile) Two things that are different, particularly two things that are superficially alike but very different in substance.
   • 1393, John Gower, Confessio Amantis:

     And thus ful ofte chalk for cheese he changeth with ful littel cost

Synonyms

• apples and oranges

References

• "chalk and cheese", World Wide Words, Michael Quinion