They are both derivatives of GABA gamma-aminobutyric acid as you can tell since both have GABA in the name. I expect that differences depend upon who takes them. I had few side effects [but side effects were the same] from either one, but the GabaPentin is mild compared to PreGabalin. For me Lyrica/PreGabalin is quite effective at controlling some of the effects of diabetic neuropathy. Baclofen is also a derivative of GABA, but it works mainly as a muscle relaxant.