The capabilities are similar. Advanced codes (EFC's) are the same (though the P key is recessed and harder to press). I'm pretty sure Key Moves (what you must mean by "copy keys") are the same. I think VPT is similar.

I don't remember the details of the differences in Macros between the 2104 and more generic UEI designs (such as the 1994). With JP1, a 2104 has macro capabilities similar to a 1994's. Without JP1 I'm not sure.

You can do a much better job setting it up with a JP1 cable than without. If you're expert enough in remote controls that you're setting one up for a friend you won't have any trouble learning the JP1 software. Get the cable. It's really worth it for the time it will save and the things that you can't do without it.