From what I know, jam is what you described as the heterogenous fruit preserve. It’a basically fruits roughly choped, sugar and pectine.

Jelly is kinda the same thing, but instead of using whole fruits, you use juice (with sugar and pectine).

Jell-o is generally artificially flavored gelatine (which comes from animal bones).

If I’m not mistaken, in Canada there are laws specifying what can be labeled as jam and jelly, like sugar concentration and stuff like that.