Sorry Ryan but they are 2 totaly difrent vehicles that just looks similar. The Nyala (RG-31) is really a police car on steroids. It was first developed here for the police. Its lighter and more controlable and its design was for tar roads up to bad dirt tracks. It was armored and mine protected because of the riots here in the late 80's and can be seen as more modern.
http://en.wikipedia.org/wiki/RG-31_Nyala
The Marauder is based on the bush war vehicles and is heavier and more armored It uses technology developed from late 70's or early 80's mostly It has a huge turn circle and is really not suited in the urban enviroment. Take it out where there is not even dirt tracks though and it will be awesome - Bundu bashing we called it in the army
(Now that is truly fun)
http://en.wikipedia.org/wiki/Marauder_%28vehicle%29
The difrences in technology can easily be seen with the windows. Nyala has large windows to see everything and the Marauder has small portals.