Apples and oranges (of two people or things) fundamentally or irreconcilably different. A North American expression, comparable with chalk and cheese.
apples and pears rhyming slang for ‘stairs’, recorded from the mid 19th century.
she's apples used to indicate that everything is in good order and there is nothing to worry about (informal Australian and New Zealand usage). The expression comes from apples and spice or apples and rice, rhyming slang for ‘nice’.
See also apple, small choice in rotten apples.