I'd say they're almost exactly like your bike shorts except the chamois pad inside of them is thinner, and they dry out fast after getting wet (swimming part of triathlon). Trisuits are basically the bib side of cycling but with the jersey part on and no sleeves. There is no neoprene-like material. Maybe 2nd guy is thinking of a speedsuit?

I used to wear cycling shorts but have changed exclusively to tri shorts. When I try on the one pair of cycling shorts I have it feels like I'm wearing a diaper. It's been relegated to 'emergency only' shorts~! I've done 60+ mile rides too.