Taste of the major 4?

[Chris84]

Hi pardon my asking, as i am really really new to wines. Im sure all of you guys would know that the major 4 red wines are; Carbernet Sauvignon, Merlot, Pinot Noir and Syrah. I really could use some help here for a thesis paper im writing. Could you guys maybe tell me the difference in their taste or perhaps how they differ from each other? Thanks a million

Chris