Browning B2000 2 3/4 vs 3inch mag, 12ga

In the Blue book there is listed a B2000 standard and a B2000 magnum but under the magnum portion it states in parenthesis, (all receivers were the same). The first B2000 I bought was advertised with 2 barrels, 1 a I/C, 2 3/4 and the 2nd a FULL choked 3 inch magnum barrel. It belonged to a friend who used them both on the same receiver. I have also and it feeds and ejects fine.
*Are all the receivers the same or is there a separate Magnum receiver and is it marked "Magnum"??
*Is the separate listing in the Blue Book just to delineate one that would have been sold with the 3 inch mag barrel?