The biggest difference is the SH-AWD. The TL is front wheel drive only, the RL has drive to all wheels. This make it handle and grip better on the bends. The RL has a bigger engine (unless you are comparing to the top of the line TL type S, which shares the same engine as the RL).I'd say that the RL is also geared towards the luxury market, ie older people. The TL is more for the younger crowd.Having owned the TL, I have to say, you should really test drive the BMW 3 series before you consider purchasing one. It is infiniately more fun to drive. The TL is not great on twisty country roads compared to the BMW, and it lacks soul. It will also develop a series of annoying rattles that the dealership will fail to fix. Apart from price, I can't think of a single good arguement for buying the TL over the BMW. After all BMW give you totally free service for the warranty of the car. Acura is going to charge you for every service.