Hi Karen
There a number of obvious changes that stand out, the mudguards are much deeper on the earlier Flash's as you can see from the pictures, also it looses its tank with the round badge and gains a pear drop style tank badge, the shroud around the headlamp (nacelle) has been removed and is a sleaker design and the hubs in the center of the wheels have changed.
There are more differences of course and also depenfing on what country you are in again there were changes for different markets around the world.
Hope this helps
Kind regards
Steve