I took the fast train from Strasbourg to Reims. You are dropped off at a station outside of town (Gare de Champagne-Ardenne) and have to connect to a smaller local train to get to the center (seems to be referred to as both Gare Centre or Gare de Reims).
The center train station has a TI. I used them to make a reservation for a tour at Mumm's, then walked there from the station. The cathedral is also walking distance. Across the street from the center station is a nice area for dining and lodging. It's a mostly pedestrian area with a string of fountains.
Maison Blanche is a small station in the suburbs - probably for people who commute by train to work. There is at least one more small suburban station (Trois something). Unless you are staying near one, you probably won't use them.
The big station is only about three miles from the center. It may not be worth waiting 15-30 minutes for a ten minute ride to Gare de Reims. Unfortunately, I didn't check to see how convenient a taxi/uber would be because I didn't realize how close it was until after I left.
Afterward I took the train to Paris and, same thing, you take a local train (or taxi/walk) out to the big station to catch the fast train.