What is the difference between a Marlin 75c and a Marlin 60?

There is no difference internal to the two rifles. The only difference is barrel length. Both have 14-round tubular magazines. The model 75C has a carbine length (~19") barrel. Model 60s produced when the 75C was in production have a rifle-length (22") barrel, but the current Model 60 has been shortened to 19", making it seemingly identical to the old 75C. My 75C from 1987 looks identical to the model 60 on the current Marlin website. If you want to see one in a bit different configuration, check out http://dillonallen.com/blog/marlin-60-aftermarket-stock-install/