Not exactly. US Jelly is more like UK Jelly (US Jello), but less viscous, yet spread like jam.

I would call US Jelly "fruit flavoured", with a high water content, no fruit solids, and occasionally even artificial fruit flavours; whereas jam is typically around 2/3 real fruit (before boiling), 1/3 sugar, with no added water, so has a denser and more "lumpy" texture.

Jelly also often comes in flavours not associated with Jam, like grape for example. (See also KoolAid, which is the US equivalent of Squash, but powdered, and also "watery" when made to manufactures instructions).