To me, a template is something you start with and then modify. "Master" page is a very unspecified term... it has no "relation" to layout. What is a "master" in layout? A master can be the primary design from which copies are made, but that is really not very similar to what master pages do...
The way master pages work today I think the best term would be "Page background". Because that is just what they are. Maybe something like "Common content"? /Peter
