which vs. what (Which sports do you play? vs What sports do you play?)

[Li Chyan]

Hello!
I am interested whether there is any difference between the following two questions:
"Which sports do you play?"
"What sports do you play?"
As far as I know, which is used when we ask about smth and there is a limited choice of reply,and what is used when the choice is unlimited. However, they can be used interchangeably, can't they?
Thanks in advance!

[Mister Micawber]

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Your understanding of the difference is correct, but often either will serve.
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Native English teacher at Mister Micawber's