Its been a long time since I took my A+ certs, but I believe what they're looking for w/ that question is this.
PCI: Its a shared bandwidth for all of your PCI slots, so the more expansion cards you have in and are using at the same time, the slower the access/use times will be.
AGP: The downside of this is backwards compatability. Since its a completely new interface, you're older PCI cards won't work if you only have an AGP slot. (I know it sounds dumb, but that's what a lot of this test is... remembering stupid junk that you won't hardly use in your professional career).
Its a frigging Laptop, not a Labtop!!!!