Stay tuned, gotta get pics.
Ok, here we go.
The series 1s all have internal extractors, the IIs can have either, the new production series IIs have the internal. Kimber had some issues with the external extractor, some pistols worked great, some horrible. Kimber scrapped the external and went back to the internal sue to customer demand(I got this info directly from Kimber customer service)
Safties, the series 1s are based on the Colt Series 70 style with no firing pin safety.
The Series IIs are based on the Colt Series 80 style with the firing pin safety.
The firing pin safety is a pin liked to the pin that holds the sear and the disconnector togeeather, that pin is lifted up by depressing the grip safety, and the pin pushes up a "button" on the under side of the slide and moves the firing pin into the firing position.
Most 1911 fans don't like the Series 80/Series II safties as it is one more thing that can break, and requires the gun to be disassemnled a little differently. Also, some guns with the series 80/series II safties are a little more fussy in operation. Some guns the pin may be too short and not ush up on the "button" as well as it should. Mainly this is due to incorrect take down and reassembly.
The difference in field stripping is that the grip safety MUST NOT be pressed in during take down and reassembly or the slide will damage the pin that lifts the "button" the pin sticks up out of the frame when the grips safety is pushed in. If done incorrectly you can damage the pin and the safety won't work.
Disabling the series 80/series II safety: Some people will remove the parts, DO NOT DO THIS, you should never disable the safety of any weapon.
Pics:
Series 1 and series II, both with internal extractors. Series I type pistol is on top.
Series II, grip safety not pressed in (active) you can see the pin inside the frame
Grip safety pressed in (inactive) you can see the pin poking out
Series 1 bottom of slide
Series II bottom of slide
I can't show the internal parts of the slide safety mechanism as it requires removal of the rear sight.
Hope this helps your understanding of the difference between the two.
Also, buy a series I if you can find them.