Salaam ,
The most noticeable difference is the front bumper and the rear spoiler , in interior their is a airbag at the passenger side , the steering wheel is much smaller made by Nardi , the RPM gauge is a six O clock needle , and the cluster gauge is black for the 1999 models only , which is also known as series 1 of series 8 , then on ther performance side the ECU is a 16 bit ( i think ) the turbos are bigger and better made by Hitichi .
Now the 2000 to 2002
rest is the same only interior is a little bit updated , they are also known as the series 2 of series 8 , the cluster gauge is white with a boost gauge , and the wheel is an update, nardi wheel.
Now the sprit R and the Rz of (2000)
Both are same cars , only difference is that Rz is way better and rare than a sprit R only 175 units were ever made ,
Now in both these cars the interior is the same, Red recaro seats , no seats at the back and has red stitching on the wheel and gear knob and hand break area , the only difference between these cars is the the Rz was only in pearl white color and in sprit R the clustre gauge has a Rotor logo in the RPM dial .
If some one give an option between a 2000 Rz and a 2002 sprit R ........... i would go for the Rz she just look pretty in that pearl white color with gun metal BBS rims ...... oh yea !!!
I think i have confused a lot of u now 
feel free to ask .
Fahd.
