From a functional basis they are pretty much the same. The difference is more in the intended use. The advantage of having 2 different Track types is it lets you do something like hiding all the FX Tracks but not the Groups. The difference is more for organizational rather than functional purposes.
FYI if you are using Cubase Pro you can use Direct Routing to send a signal to 2 (or more) different Group Tracks - so you could use Groups for both your close & room tracks.