790FX - Very high end, supports 16x/16x, 16x/8x/8x, 8x/8x/8x/8x CrossFireX, ATX motherboards.
880G - Relatively budget, mainly µATX, one 16x PCI-e lane, some come with a second at 4x, same situation with 770 chipset, native SATA III support, some with USB 3.0, has integrated Radeon HD 4250 graphics.
890GX - Higher end, ATX form factor, supports 8x/8x CrossFireX, comes with integrated Radeon HD 4290 graphics, native SATA III support, some with USB 3.0.
890FX - Highest end for AMD at the moment, all ATX form factor, supports 16x/16x, 16x/8x/8x, 8x/8x/8x/8x CrossFireX. Native SATA III support, some with USB 3.0.