Hardcore gamers have more knowledge of the industry. It goes beyond, "I like Call of Duty so that's the best franchise, ever." Hardcore gamers will make profiles on gaming websites, know the release dates for certain games, know when their company is doing good or doing bad, or actually know what Capcom, Konami, Platinum Games, etc. are.
Casual gamers: Probably won't check reviews, look online for info, give DLC a second look, or even play online. Their experience is basically, "This looks fun so I'll buy it" or "I saw somebody playing this and it looked like they were having a good time".
There's varying levels of both. There's the Hardcore gamer that plays a certain game for an insanely long amount of time, mastering the nuances and intricacies of a single specific title. There's the casual gamer that buys every game but never plays them. There's the hardcore game that only plays one genre. There's the casual gamer that knows about the industry.
While I don't think there's such a thing as a hardcore game or a casual game, I do think there's such a thing as a hardcore gamer and a casual gamer. There are probably some pretty hardcore Wii Play fans out there if you know where to look.......and I do.
