Used to ask for a specific choice among several options. Often appears in questions or embedded clauses.
Please choose whichever one you like.
One of them is the correct answer.
one of; any of
Refers to an unspecified item from a group, often in statements rather than direct questions. Can imply 'any one will do'.
Lend me any one of them, please.
どれかが当たりです。
One of them is a winner.