Are macaroons cookies? Are all coconut cookies macaroons?
There are two ways to look at what the difference is between a coconut cookie and a macaroon.
On one hand, a macaroon is a type of coconut cookie.
On the other hand, and how I prefer to look at the world, a macaroon is a Cookie, but it's not a cookie. That is, it's in the family of sweet, finger size, baked treats that can be crisp. A brownie is not a cookie because it retains its cake- or fudge-like character. However, when one bakes up brownies so thin that they become "brownie cookies," they can become a cookie.
Nevertheless, ceases to be a macaroon and exists as a "cookie" once enough flour is added so that it flattens out and becomes less "fudgy" in the middle and crisper around the edges.
Normally, a macaroon is thicker and more rounded than a traditional cookie, due both to the structure of the coconut itself and the whisked egg whites providing some structural support. I'd put macaroons, which are characterized by containing nut flour and whipped egg whites, in a separate category from cookies (which we are understanding to be distinct from the broader Cookie "food group" and referring to flattened, sweet, flour-based finger sized baked goods).