From: (Steve Deering) Newsgroups:

Here's a list of differences between the Elan II and the original Elan.
I have tried to be thorough, rather than just listing those differences
I consider important -- many of these items will be unimportant to most
people, but each might be important to someone.

Disadvantages of Elan II compared to Elan

- larger partial metering area (9.5% vs. 6.5%).
- no partial metering circle in viewfinder [*].
- film advance noise is louder.
- slower continuous shooting rate (2.5 fps vs. 3 fps).
- smaller metering range (EV 1 to 20 vs. EV -1 to 20 @ ISO 100).
- no camera shake warning indicator in viewfinder.

Advantages of Elan II compared to Elan

- metering scale for manual exposure mode.
- separate dials for setting metering pattern, AF mode, and film advance mode.
- available "AI Focus" mode.
- 3 autofocus points.
- 3 partial metering areas.
- eye control of autofocus point, partial-metering area, flash-exposure-lock
  area, and depth-of-field preview (IIe only).
- can swap AF lock to the AE lock button, via custom function.
- accepts wired remote shutter release, as well as the wireless one.
- when mirror-prefire custom function is selected, self-timer delay is
  reduced from 10 seconds to 2 seconds.
- self-timer countdown is displayed in the LCD panel.
- leader-out rewind option.
- "silent" rewind option.
- available AA battery pack / vertical grip with shutter release.
- available external D-cell battery pack.
- option to fix shutter speed at 1/125 when using flash in Av mode.
- 4 zone, 3 point TTL flash metering for built-in flash and older Speedlites.
- able to use the following features of the Speedlite 380EX:
    - evaluative flash metering (E-TTL)
    - flash exposure lock
    - flash exposure compensation
    - high-speed flash synch
    - second-curtain synch

Other ways Elan II differs from Elan

- built-in flash does not zoom, but is more powerful [**].
- different evaluative metering pattern (may reduce exposure accuracy).
- different user interface for setting ISO, AEB, red-eye reduction, flash
  compensation, multiple exposures, and beeper tone.
- left-side strap lug is on side of camera, rather than front.
- "retro" cosmetics.
- no bar code reader.
- negligible differences in weight, camera dimensions, viewfinder coverage,
  viewfinder magnification, and eyepoint.

* There is a small, circular area in the center of the viewfinder that
  is slightly clearer than the rest of the viewfinder, but this is
  smaller than the partial metering area, and is present in both cameras.

** The lack of zoom capability in the Elan II built-in flash eliminates
  the worst source of noise in the Elan.  The Elan II flash is stronger
  (at 28mm coverage angle, ISO 100, the Elan II has a GN of 43 ft., vs.
  39 ft. for the Elan), but it is unclear to me whether or not that makes
  up for the lack of zoom capability.  According to the brochures, the
 "coupling range" of the Elan II flash is 3.3 ft. - 15.1 ft., while the
  coupling range of the Elan flash varies from 3.3 ft. - 12.2 ft. at 28mm
  to 3.3 ft. - 10.6 ft. at 80mm.

One other difference is that the eyepiece on the Elan II is larger than on the Elan, which means that the standard Canon eyepice magnifier and right angle viewer will no longer fit. I believe there is an adaptor for the right angle viewer (Angle Finder Adapter Ed). I'd guess this will also fit the Magnifier S, though Canon don't mention it in their literature as far as I can tell.
Bob Atkins