The XCAR team has recently reviewed the BMW E30 M3 against the BMW E92 M3 GTS. These two are already very superficial in their separate world knowing well that they are from different eras but each one of them had and has its own heroic moments. As for BMW enthusiasts differentiating the two is utterly impossible and the difference could only be told on the road just like Xcar did in this review.
The team explains well starting with the E30 M3 which was the first ever M3 in the M-Powered cars lineage, it boasted of prowess in the road as opposed to its counterpart the E92 M3 GTS that boasts of prowess on the track better. Of course the GTS came 26 years later when racing technology was at its peak; BMW made only 150 examples of the GTS each coming with a sport package featuring a roll cage, lighter weight than the ordinary M3 among other features.