What are the differences between the Suzuki GSX R 750 and the Suzuki Katana 750?

it depends on year of gsxr the 85 -91[every where but us 92 for usa] were air/oil cooled and so are all the katana's. the gsxrs were more for all out topend power and the katana has more low midrange power both bikes are good bikes just the katanas are a down tuned version of the gixxer hope this helps