I've never used any of these adjectives to describe games other than "casual", and I usually am referring to games that are easily accessible, simple, and don't take a considerable time investment to play (iOS games, some puzzle games, etc).
Also, I get the feeling "kiddie", "mature", "hardcore", and "casual" to an extent are more marketing terminology used to detract from another console/game series, then console "fanboys" (more slang for you) trumpet that same wording that the company uses.