I layered them over Essie Lapis of Luxury (3 coats) and Essie Mesmerize (2 coats) and they sure did look alike. The biggest difference I noticed was the glitter in Hottie was denser; I needed two coats of Party Palace Blue to match one coat of Hottie.
I definitely don't need both of these. I like the Confetti bottle shape better, but since the Sinful covers better, I think that gives it the edge.
Edited 12-Jul-2010 to add this photo showing the Sinful on its own: