Boat is usually translated as "човен", but there could be some overlap I would assume
Arrr, ye land-lubbers not be understandin' tha difference b'tween a boat and a ship! OK, seriously. I would assume that the difference between a корабель and a човен would be the same as the difference between a ship and a boat in English. Right? A ship is a boat, but a boat is not a ship. A ship is like a big boat.
maybe it has some common background with the word carabela/corvette/Korvette?