When spoken by most Americans, -burg and -berg sound the same (kind of like "burr g"), and incorrect!
A fortified town was called a Burg (pr. bourk). A mountain is a Berg (pr. beark). When named, Salzburg and Rothenburg were fortified towns (Rothenburg still is). On the other hand Nürnberg was so named for the castle that sits on a hill. The buses for the Eagles' Nest leave from Obersalzberg, Upper Salt Mountain, which is just a few km from Salzburg, Austria (a fortified town on the salt trade route).
This is important because much of the software for searches and train schedule won't come up with the right place if you spell it incorrectly. Put in Salzburg on the Bahn query site, and you'll get Mozart's birth town. Put in Salzberg, and you'll get a pulldown menu with bunch of choices. The first few will be towns in Baden-Württemberg or Hessen; the town in Austria will be well down the list.
Also, those two little dots over the vowel, called an umlaut, are important. Füssen is NOT Fussen! However, using "ue" for "ü" works (and is, technically, correct). So, if looking for a route to Neuschwanstein, use "Fuessen Bahnhof".