Kent - yes - the line that went through Union Station is still there. Its the freight main line. The building itself is completely gone, replaced by a strip mall. (I don't like it either :-))
Bangor Yard is the largest difference - it used to have a round house, its own work train, a back shop and a large yard. Its GONE. There is a single track through there and the land has been turned over to the City and its been turned into a multi use area, walking trails, outdoor concerts etc.
One of the reasons that Bangor yard was so big, the Calais branch, was shutdown in the early 80s. At that point, Bangor yard wasn't nearly as important as it once was.
Recently, a portion of the Calais branch was re-activated, its now being used as a Tourist operation, the Downeast Scenic. However, they are 'rail locked' with a rail trail to their East and no actual interchange to their West.
-Joey