Right off the top of my head, the biggest diff for me is that M205 has an incredibly long work time compared to M105. Don't let that sucker you into not cleaning the pads often enough, even with the reduced cut you oughta clean/reprime/etc. them now and then.
As for pressure, I sometimes use *more* with M205 because of the reduced cut. But I kinda push the envelope with M205 upon occasions, using it with orange (and esp. the orange Griot's pad) to get some actual correction out if it (even if it *is* a "finishing polish").
The number of passes will depend on what you're trying to correct *MUCH* more than it will on the work time of the product. Prime the pads properly and I bet you'll find M205 a lot easier to get the hang of than M105 was.