If by related you mean both are bony fish. They look a lot alike, but are about as closely related as bettas and sturgeon. Bowfin are part of the order Amiiformes, a very ancient order of fish. Bowfins are the only living members of this order. (The US has a lot of ancient fish hanging around like gars, bowfin, and sturgeon.) Snakeheads are part of the order Perciformes, the most recently derived bony fish. They do look a lot of alike, and when the snakehead scare started in the US people would commonly mistake bowfin for snakeheads. They would kill the bowfins thinking they were the invading snakeheads.
You've got a neat piece of fish evolutionary history there!