Jelly has never had a place at my table. It is watered down jiggly nothing. Jam, however, is full of real fruit and, even though I rarely have it, there is not much more enjoyable on a cool morning that a fresh hot biscuit with blackberry jam.
We say jam for the preserved fruity spread used on toast in Australia. The thickeners are sugar and pectin; there's no gelatine in it.
Here, jelly is a different substance - wobbly, sweet, translucent, and served after dinner. It's made with gelatine (using crystals of purified cartilage and bone) and fruit juice, often with pieces of raw, ripe, whole fruit suspended in it.
A vegetarian/vegan version can be made with a type of seaweed called agar-agar.
A savoury version called brawn is sometimes made using soup stock, vegetables and meat, poultry or fish.
I think I got it figured out: American = UK/Australia Jell-o (gelatin) = Jelly Jelly (No fruit pieces) = Jam Jam (Sm fruit pieces)= Jam Preserves (Large fruit pieces) = Marmalade Marmalade (citrus fruit rind) = Marmalade
Thriftymaid 