no real difference really mate apart from the already mentioned bumpers front and back (90 spec bumper got bigger vents to aid cooling),erm rear spoiler is different(bends over at each side rather than folding around on the earlier spec.also the interior was updated to red grey and blue specks,i think it was called zolda whereas the older one was just red and grey speck.temp gauge on some of the later models was on the far right i.e petrol then temp but again earlier ones was other way round,the only other thing i can think of is the rear lights on a 90 spec came standard with smoked lenses,i think thats it of the top of my head,might b more but thats all i can think of at the mo.
hope this helps
rick e