There is no difference on any of the esc world cars ive seen or worked on....

The steel versions were produced by the people who modified the shells fo boreham and were as Damo says beaten out....

Kevlar mix versions are exact copies of the steel versions....and do fit extremely well....the silver car looks different from the rally car....cant 100% tell but i suspect it has wrc wings and standard rear quarters..
HTH

Ian