The 50i has the following differences from the 35i:
Bigger engine (doh)
Numerically lower final drive ratio
Bigger battery
Slightly worse drag coefficient
Bigger front brakes
Different wheels
Different colour grille
The following items are options on the 35i, standard on the 50i:
Self leveling rear suspension
Auto dimming/folding exterior mirrors
Auto dimming interior mirror w/compass
Homelink
NAV
Ashwood trim
Ventilated seats with perforated leather are an option on just the 50i.
No word on the full leather package.
You can still only order headlight washers as part of the silly Activity Package. Dumb.
The standard/optional equipment above may be different in your market if you are not in Canada.