Outside of the theme and the route/network building, the games are completely dissimilar. RRR is a worker placement game, while Trains is a deck builder. i always felt like Trains is Dominion with a map tacked on. In RRR, the map is central to play.
Railroad Revolution is not a worker placement game. There is no shared pool of actions you use workers or similar to claim and block others from using. It is a straightforward network building resource management and growth game with race elements because of the benefits of being first to a particular location.
Quite dissimilar from Trains, of course.