The aesthetics are very different, the stations are vast tunnels with deep platforms, and the trains are fast and silent. On the platform there are lit panels indicating the precise direction and list of stations the next train will be serving.
All trains stop at all Paris stations.
Be careful at Nation and Etoile that you haven't mounted a train on the correct line but the wrong branch. Otherwise, you'll have to circle back and pay another fare. Controllers often stake out the Vincennes RER station catching hoards of violators in their net. Also note that on those lit panels the name of the train and the time of arrival is posted. The trains have funny four-letter names which are written in lights on the front of the first car.