Mk1 had the smaller rear window,
different front grille,
rear lights,
the rear quarter windows had the piano hinges on them but the Mk2 had them too,
The switch panel is slightly different, its more skinny and lengthy if that makes sense? Difference in shape. The cooper had the Grey cumulus switch panel and the normal ones like a creamy/white one I believe
The very early mk1 binnacle attached to the car via the a front speedo housing which you can tell by 4 screws in a square around the speedo and hooked to the body as well where as the later ones and Mk2 onwards the binnacle screwed straight to the body
Mk1s had the floor starts and dip switches on floors (not all I dont think) but they never had them on the Mk2
Mk1

and Mk2