@coopey certainly they imply different things. Back in the day, Pnut decided to use "bookmark" officially, but it's still used periodically as a like/star/favorite (which I think are indistinguishable).
@coopey star is totally arbitrary. like/favorite have issues around "do I do this action only if I liked it? what about cancer/war/etc?" bookmark has a clear purpose, and doesn't suggest the other purposes. Upvoting, visibility, appreciation.
@coopey despite it being a bookmark, pnut still uses it for visibility, appreciation. API is only slightly opinionated, and the idea is to let people build on top however they want.