The archetypal constructs they represent would suggest not. Pumba is the large, dumb, well meaning muscle of the group, timon is the small, fiesty, intelligent one. Pumba occasionally stumbles into trouble in a clumsy, well meaning fashion, and Timon has to talk them out of it. Timon more frequently gets into trouble either through his short temper, or smart mouth, and pumba has to step in and try to calm things down, or protect his buddy in a fight. Subtle variations are always possible, but in general, Timon is the smart one and Pumba the strong one.