what is the difference from a std. z3 and a roadster?

All convertible Z3s are considered roadsters. The only Z3 that is not a roadster is a Coupe which is a hard top hatch back.

It's either a 2-door convertible or 2-door coupe. The difference are in the engines of the various models. The 1.8 & 1.9 litre have 4 cylinder engines.The following models have 6 cylinder engines. 2.0 litre 2.2 litre 2.8 litre 3.2 litre 3.2 litre 2.5 litre 2.5 litre 3.0 litre 3.2 litre

However if you're refering to the Z3 M Roadster (1998–2002) there are alot of changes.It being a performance version it is highly upgraded from the standard Z3!

is there any outlook difference between indian z3 and german z3?