Wotcha and welcome Neil, great cars the P1 and TypeR. Off top of head think the RA has 4 doors but I also believe there are mods like alloy bonnet to make it lighter, Im on tapatalk so cannot get the links to a Web site which details differences, it is in a couple of threads already if you search the impreza part of the forum.
Someone else will probably fill in the gaps but if not ill dig it out later