The bottom line for mame4all is that it's a faster version of an old version of mame. The emulation generally isn't as accurate, but I think a few of the cores have been ported to assembly. Also, mame4all doesn't have as many configuration options. One place you'll notice is on, say, the neo geo games which won't run full speed on advmame. I haven't seen a table of roms that work at 100% with the pi2, but if you establish such a thing, let me know!