Like that ;o.

I think you're casual if you play a game that is instantly fun there and then, and when you quit the second something isn't fun anymore.

Hardcore gamers are those that put up with hours of boring crap to excel at the game later. Like Disgaea grinding. Or WoW grinding for that matter. Maybe practicing an FPS because it's fun to win against others, even if the actual practice isn't fun.

These are of course not absolute definitions of either terms, but probably at least *one* definition of them.