Great... now I'll get confused too!
Perhaps we should just think of "riba" as "jellyfish" and cover both Hebrew and Russian ;p
Jam is never called jelly in Australia to mean jam, even if the jam is set like jelly. Now I have confused you. But jam is spread on bread, jelly is eaten with cream or icecream.
If you can't use apostrophes correctly, you can't say others are ruining the language :P
No, jam and jelly are different things. And it's actually the Brits who've ruined it, http://www.bbc.com/culture/story/20180207-how-americans-preserved-british-english
Just to confuse matters even further, the Android app for this lesson only allows "marmalade" as an option.
That's incorrect English. Neither bread nor jam take the article "a". You can talk about a loaf of bread, or about a container of jam, but as far as I understand it, "bread" and "jam" are both collective nouns.