I see a lot more jam around than jelly here in Oregon, but the words do get used interchangeably sometimes -- When people talk about PB&J they mean a peanut butter and jelly sandwich, but the "jelly" is often strawberry jam -- though I guess grape jelly is the most "traditional".
The shelves in the stores here have blackberry, boysenberry, raspberry, strawberry peach jams -- preserves -- and marmalade made with citrus.
People do tend to eat apple/mint jelly with lamb.
Mostly jams and jellies are spread on toast at breakfast.
Jello is a fruit flavored dessert -- or salad in the Midwest -- that is made by adding a packet of fruit flavored gelatin to hot water and refrigerating it till it sets up.

Blessings,
Barbara