Yeah, having flown quiet a bit in both the EU and the US I can say for sure that the major American airlines (Delta, United, Southwest) are far more comfortable than European budget airlines (Ryanair, EasyJet, etc.) in economy class. They usually offer a bit more leg room, complimentary drinks, and might even have wifi on shorter hops. LGA -> ROC (a quick 45m hop) on Delta has both!

That being said, perhaps a better comparison would be Ryanair vs Spirit, but American budget airlines are still pretty limited in routes and aren't nearly as entrenched as their European counterparts.