To me, I think there are many levels of gamers:
*disclaimer - the following is based on nothing but my own thoughts and do not mean to offend anyone belonging to any level:

- light gamers: people who might own a system but not remember the last time they played it or what the last game played or bought was

- casual gamers: (most people) people who play in their free time (with no planned amount of time to play) several times a week and go to a electronics/gaming store weekly to bi-weekly to either purchase or browse and more than likely have a gaming mag subscription

- hard-core gamers: to me, these are the gamers that nightly (or nearly) turn-on or log-in to a game to play with the intent of playing game "X" with live-chat combat or other interaction till their real life requirements (food,shelter,bio-breaks, girl friends) require attention. (ie. unreal, 360 combat sims (I dont own one so I dont know,) or even PC titles like EQ, WOW, or LOTRO and yes, I play/ed two of those) They are likely recognizable at the local game stores by employees and the casual gamers because of weekly trips to those stores and are also more likely up-to-date with what is going in gaming news.

Again, this is just my opinion

in short, hardcore gamers play a lot and can usually complete a game story in the minimum amount of estimated time with little or no restarts. Casual gamers play through it casually, trying to get the most fun out of it as opposed to beating it. Light gamers wont even touch games like that, they may buy a simpler game like a racing game or a flight sim, something straight- forward.
Based on years of research (mostly just playing games and talking to ppl about it) ppl may consider the wii system to be for the 'non-hardcore gamers' but i think that with some of the most recent titles (i.e. Soul Calibur Legends, Manhunt 2 and LOZTP) prove the wii isnt just a family system, but for gamers who want to feel more into the game, we are evolving as a video gaming community, and the XBOX360 and PS3 are still stuck in the past.

The Dodo JZ

here here! I like the way you put that too.

Yes that was very well put.

here here!