Here's a good summary lifted from the great Medium Format Megasite, which lifted it from somewhere else. I have included the original poster's name:
<start of quote>
From: Duncan Ross
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Medium format rangefinders (M7 -vs- M7II)
Date: Sat, 14 Dec 2002
Here is a comparison based on my 7 and 7II.
The 7II has the following improvements over the 7:
1) A relocated cable release socket (The 7's is by the button release, the 7II is on the lower side of the left hand grip.).
2) An improved darkslide curtain winder. The 7II has a flip down winder, the 7 has a recessed knob. I have to remove the 7 from the tripod to engage the curtain and change a lens. I use the RRS tripod plate and it comes pretty close to this knob. (You may not find this a pain if you use the Mamiya tripod adapter or something else).
3) A different type of button arrangement on the exposure comp. The 7 is a 2 button control (one to release the lock) where the 7II is a single button for lock release and adjustment (push then turn)
4) A brighter viewfinder (though I don't really see much of a difference)
5) The 7II has multiple exposure capability.
6) The 7II has a chrome plated battery cover, the 7's is black.
7) The 7II has the word MAMIYA embossed in raised letters on the left hand grip. The rubberized material for the grip is the same, though.
8) The 7II has an extra strap mount so the camera can be hung
horizontally. The strap lugs are chrome on the 7II, rather than black.
All in all, they are very equivalent depending on what drives you nuts and your use. I don't like removing the 7 from the tripod to change lenses). The 7's viewfinder can be upgraded or under $100, but it's really not all that different. Since many people do multiple exposure in photoshop these days, I can't understand paying much for this feature. <end of quote>