2-door shell, different bodywork all over the place (including wider arches), 2.2 engine instead of the usual 2.0 (it's the same lump though, just bored-out a bit), different suspension setup, and loads of other stuff.
At the time, it was touted to be the ultimate Impreza - factory-built to compete with all the nutter modified ones. In practice, it wasn't really much better than the already-very-good "normal" Impreza - and they're *way* overpriced these days.
I suspect the ones currently living in the UK, can be counted on your fingers ? Is there a way of finding out this sort of thing ? Would the DVLA tell me ?