Basically, here's what it boils down to:
RPG Maker is made for making RPGs. It's good at it. It's flexible enough to make a platformer, but it's a headache. (Only true with RMXP.)
Game Maker is made for making platformers, shooters and other, similar games. It's good at it. It's flexible enough to make an RPG, but it's a headache.
The flexibility of both systems is necessary when you want to do something that's a little out of the ordinary. (Both GML and RGSS are equally powerful.) I admit, Game Maker doesn't come with much in the way of graphics or sounds, but there are a lot of free resources out there (like those on this site :D ). On the other hand Game Maker is 1/3 the price of RPG Maker.
Anyway, I (personally) wouldn't try to make a console-style RPG with Game Maker, and I wouldn't try and make a platformer or shooter with RPG Maker.
Edit: Doh. I didn't notice how old this thread was. Sorry about that.