Both macarons and macaroons are confections, and both names are derived from ammaccare, which is Italian for "to crush" — but that's where the similarities end.
A macaron specifically refers to a meringue-based cookie made with almond flour, egg whites, and granulated and powdered sugar, then filled. The delicate treat has a crunchy exterior and a weightless interior with a soft ending that's almost nougatlike in its chewiness.
A macaroon is a generic phrase that is applied to a number of small, sweet confections. Mostly, the term is equated with the moist and dense coconut macaroon, which is composed of egg whites, sugar, and dried coconut, often piped with a star-shaped tip, and sometimes dipped in chocolate.