...og til slutt denne delen som omhandler betegnelsene i forhold til utstyrsnivå etc 
Okay, it's generally quite simple, it's when you get down to the options list that things get complicated. Let's do the import versions first. You've either got the normally aspirated version (generally called the NA or N/A) or the Twin Turbo (TT). The NA version comes in three flavours...
SZ-R
SZ
SZ-R Aerotop
...and the TT comes in four...
RZ-S
RZ
GZ
GZ Aerotop
So, fairly simple then. Now into this mix you've got the original UK version of the car, but this is dead simple because there's just the one model - the UK TT. There are no UK NA versions and no UK Aerotops.
However, Toyota then mucked about with the model designations of the RZ in 1995. The RZ became the RZ-S and a 'new' RZ was introduced. So for the RZs there's a bit of fiddling about to know what's what:
RZ (1993 to 1995) - the 'original' one
RZ-S (1995 to 1997) - equivalent to the 'original' one
RZ (1995 to 1997) - the 'new' one
The only reason you need to keep an eye on this is because the 'new' RZ had bigger brakes and 17" wheels as standard. But these were options on the 'old' RZ and RZ-S anyway so you might find these models with these extras fitted too. This is actually a perfect introduction to the unpredictable world of the Supra options list - model designations and options is a tricky area to cover as there is a lot of conflicting information around. The problem is that a lot of the info online is in Japanese, and much of the remaining info applies to the US models, and they have market-specific versions such as the SE (Special Edition, which contrary to what you might expect to find on a special edition version actually had all the extras stripped out and was effectively a 'super basic' version) and also the 15th Anniversary model that simply had extra badges on the outside! However, we're most interested in the right hand drive versions, and from here on in things get a bit woolly...
Firstly it's worth pointing out that although the Toyota sales brochures list what the various options are on each model there seems to be a tremendous amount of overlap and very little is set in stone. Maybe the local Toyota dealers were happy to bung on whatever the customer wanted, or maybe the customers themselves bought and fitted extra bits - who knows. The Japanese love to customise their cars, and also bear in mind that owners in the UK put on extra bits and bobs too. With some cars having passed through 3 or 4 owners it's no wonder it's getting tricky to work out what is original, what was a factory fitted option, and what was fitted by a previous owner. There are also some little quirks such as certain options being dependant on if you have a manual or auto gearbox even though they both have the same model description. Bung in Toyota's own fiddling about with the RZ models and you start to get an idea of how difficult this subject area is and why it appears there is no definitive source of info.
The UK TT has several important differences to the J-Spec versions - full leather (the GZ also has 'full' leather but the rear seats are actually leather-look vinyl), heated front seats, headlamp washers, bonnet air scoop, plus several other more technical differences. The facelift Supras again have several differences that are worth looking out for on the cosmetic side of things. The most important mechanical difference was the introduction of the VVTi engine. The Variable Valve Timing ('intelligent' - hence VVTi) gives an extra 5bhp on the NA version and 25bhp on the TT. The other major mechanical difference was the introduction of the Tiptronic gearbox - this can be left to act as a full auto gearbox or you can manually change the gears using two buttons on the steering wheel. Tiptronic cars are still relatively scarce in the UK.
When you go to look at a car probably the best advice you can have is to treat each car as effectively a unique model. And because the optional extras list is so varied sellers frequently get the designation incorrect anyway, so take more notice of the actual extras listed and not the model identification.
So, the key points to remember are...
The UK model is the highest spec of all.
The GZ model is the highest spec Import version.
There are no UK Aerotops
There are no UK NAs
There are no UK Facelift models
There are no UK Tiptronic models
There are no manual Aerotops (yes, you read that right - all Aerotops have automatic gearboxes, both NAs and TTs)
VVTi models are all facelifted
Tiptronic models are all facelifted
Understanding the J spec model designations is a little tricky but okay once you get the hang of it.
The SZ-R is the base model. NA engine, 5 or 6 speed manual gearbox only, and a limited range of optional extras.
The SZ is the top-spec NA hardtop model. NA engine, auto, 5 or 6 speed manual gearbox, a few more options.
The SZ-R Aerotop is the only NA Aerotop model. NA engine, auto only, a few more options.
(so the SZ has more standard fittings than the SZ-R, but the SZ-R Aerotop has the same fittings as the SZ)
The 'original' RZ is the entry level TT model. TT engine, auto or 6 speed manual, limited range of optional extras.
The RZ-S replaces the RZ as the entry level TT model. TT engine, auto or 6 speed manual, limited range of options.
The 'new' RZ is the middle spec TT version. TT engine, 6 speed manual only, a few more options.
The GZ (inc. Aerotop) is the top-spec TT model. TT engine, auto only, some options fitted as standard.
(when the GZ stopped production the RZ became the top spec model)
The attached Excel chart gives what I believe to be a pretty accurate documentation of the various model differences available, having been pulled together from sources scattered around the interweb. This covers the NA, TT, Facelift NA, Facelift TT and UK TT versions - basically anything right hand drive. Note that on this chart I've marked the facelifted cars as starting in 1998 since this was when the 'full' facelift took place (cosmetic + mechanical changes). It's also worth noting the oddity of 1996 Supra production - it appears that Toyota were gearing up for the facelift and decided to ditch a number of options. The wood or carbon fibre dashboard panelling was unavailable this year (presumably so Toyota wouldn't have to manufacture a new supply of pre-facelift dashboard pieces and run the danger of having some left over that they couldn't sell), and the electric drivers seat was unavailable on many models as well (although in most cases somewhat oddly it was a standard fitting pre-1996 and was a standard fitting again from 1997 onwards - quite why it couldn't be fitted in 1996 is a bit of a mystery). 1996 appears to be the year that the options list was revised as this marks the year when many options became standard. Items such as airbags, leather seats and ABS either went from optional to standard to from unavailable to optional. So as far as can be determined Supra production looked something like this:
1993 - Supra introduced in UK and Japan.
J spec range: SZ, RZ, GZ, GZ Aerotop.
1994 - SZ-R introduced in hardtop and Aerotop versions. 17" wheels and bigger brakes available as optional extras on all J spec models.
J spec range: SZ, SZ-R, SZ-R Aerotop, RZ, GZ, GZ Aerotop.
1995 - RZ-S introduced to replace 'original' RZ. 'New' RZ is manual gearbox only with 17" wheels, bigger brakes and active spoiler as standard. Last TT Aerotops produced.
J spec range: SZ, SZ-R, SZ-R Aerotop, RZ-S, RZ, GZ, GZ Aerotop.
1996 - Last GZ models produced. Some previously standard fittings unavailable on some models. First cosmetically facelifted cars start to appear. UK model ceases production.
J spec range: SZ, SZ-R, SZ-R Aerotop, RZ-S, RZ, GZ
1997 - Some fittings go from unavailable to optional or from optional to standard. VVTi, Tiptronic gearbox and REAS all introduced. RZ model now has Recaro seats.
J spec range: SZ, SZ-R, SZ-R Aerotop, RZ-S, RZ
1998 - Last SZ-R Aerotops produced.
J spec range: SZ, SZ-R, RZ-S, RZ
2002 - Supra production ceases.
J spec range: SZ, SZ-R, RZ-S, RZ
.