These 2 stations are not the same station but rather 2 stations quite close to each other. Fernbahnhof (tracks 4-7) is where the long distance trains stop and Regionalbahnhof (tracks 1-3) is where (most of) the regional and local trains stop. The 2 stations are connected via a walkway. The street address of both stations seems to be the same, so that's not going to help.

My trip has a transfer in Frankfurt and I am arriving at Frankfurt (M) Flughafen Regionalbf. From there I am making a 15 minute transfer to Frankfurt (M) Flughafen Fernbf. QUESTION... 1) Are these two the same train station? 2) What are the physical addresses to both these stations?

Thank you in advance

 

These are 2 seperated stations within the Airport as already mentioned there is a walkway. 

Just incase you use a Flexipass note that this trip would take 2 Traveldays you may catch the ICE619 on a earlier stop to use just one travelday. 

Next advise dont reserve via Eurail it´s more expensive and you have less options. I recommend to reserve via bahn.com. This is cheaper and you can select specific seats.