It's a recent thing.
Of late, the macaroon is the coconut biscuit that Mrs Overall could whip you up in an instant, and macarons are those meringue type things sandwiched together.
The joke was, when I was a kid, that if anyone asked you if you wanted a scone with your cup of tea, was to reply politely, "No thank you, I don't like scones, have you any scones?" (Pronounced differently , of course).
According to me, macaroons are made using meringue and coconut with a cherry on top and very nice they are too. Macarons are tiny little smooth brightly coloured things which are sandwiched together. I've never had them but I bet they are yum
I think the word is used for two different confections just as there are two different types of muffin, the ones you toast and the ones which are little cakes (three types, if you include the mule).