F-body brakes refer to the specific brakes that came on the LS1 f-bodies (Camaros and Firebirds). If you don't know what an f-body is, you can read here:
GM F platform - Wikipedia, the free encyclopedia
W-body brakes refer to the brakes you already have. There are 11" versions and 12" versions, depending on what w-body you're talking about. For more info on what a W-body is (like your GP), then read here:
GM W platform - Wikipedia, the free encyclopedia