1 - Graphics Communications is more digitally-oriented, with modules and paths going into web design and 3D animation.
2 - Graphics Design is slightly more traditional, and arty-designy, focusing slightly more on 2D designs such as magazine/advert, with more need for creative designs than technical web scripting.
3 - Media is closer to sociology than art, and there tend to be a bit more of TV and radio in it.
4 - Illustration is just on the edge of fine art, very much using traditional techniques.
For most of them, especially the more digital options you need to have experiences in the Adobe Creative Suite (think somebody said that), for Media you need to learn stuff like After Effects and Soundbooth, for Graphics you definitely need Photoshop, and preferably some experience with InDesign (magazine layout) /Illustrator (vector art) / Flash (web-based interactive content).
Oh, and if you consider going 3D (not necessarily for games), Maya is the industry standard.
I myself just browsed half of the creative arts forum over the entire night, knackered, but hopefully my own deductions will help, and please correct me where I'm wrong.
p.s. if I want to study graphics design/comm., I have a mix of foundation and undergrad applications, do you think these are okay?
FOUNDATION
Loughborough Uni
Central Saint Martins (UAL)
Dundee Uni
ECA / GCA?
UNDERGD.
Brunel Uni
Southampton Uni
Goldsmith Col.
Nottingham Trent?
I'll thank God if I get into half of these, but are they very good at what they do? And are they broad?