Simplistically, a ship can carry a boat, but a boat cannot carry a ship. But you could debate this for a long time. I have done. To quote a friend (and Ship Science graduate) that I have posed this question to in the past:

“There’s no right answer because there are always exceptions. The ship carrying a boat thing works a bit but not for a fishing boat, for example. A ship is generally an ocean going vessel but then that doesn’t work for submarines which are always boats. Or over 500t, always exceptions to that too! A sailing ship is one that has 3 or more masts with yards crossing them – but i don’t suppose that helps much!”
Vicki Franks, Cambridge, UK

Thanks to MiniBoyGeek for helping to make me the owner of a ship 😀

Yes that is a bath toy boat floating in a bath on a narrow boat floating on a narrow canal, and we are also halfway up a hill (perched on the side).