Hi,
The earlier six cylinder engines did not have VANOS (variable valve timing). In New Zealand the Vanos motors were introduced around about 1993.(we get Euro spec cars)
I have only driven my car, which has Vanos, so can not tell you what the difference in power feels like when driving them.
I think I read somewhere that the cam profiles are different, which makes the engines feel quite different to drive.
Also sometime in 1996 they started making the engines with alloy blocks.
My car was made mid 1996 and has the alloy block engine, which I think was officially released in 1997.
Hope this helps
Cheers
Rossco
1996 E36 320i