Hey Kirk,
I own both, Martin and Master. My Master is a dry tune in D and my Martin is also a D with a wet tunning. Any difference? One difference I have notice is that the fingerboard on my Master is slighty shorter in length. It seems like my fingers are curl more when I play my Master. Both good instruments, I love playing them both. When I put them side to side, I do not see any other difference in appearance. The Martin has a thicker varnish coating is about the only other difference I can see. Sound wise, they both rock, in my own words.
Later gater
Mark S