Go to the legal forum and read the findings in the Heller vs DC decision. Here is an excert
the Second Amendment has so far been read to protect only “a personal right to keep and bear arms for lawful purposes, most notably for self-defense within the home.” McDonald, 130 S. Ct. at 3044. While one or two firearms may be necessary for such purposes, a large collection of weapons is not. The Constitution, in short, guarantees the right “to keep and bear arms,” not the right “to keep and bear an armory.” As an individual seeks to acquire more guns, he moves farther and farther away from the right to bear arms and closer toward the constitutionally unprotected goal of assembling a personal arsenal.
A lot of legalese to wade thru but it is interesting (and a bit scary) reading.
Seems they are using the terms interchangeably.