scroll to the bottom to find links to Colt's 2013 catalog that will list the differences. The big one is ~80mb
http://www.coltsmfg.com/Catalog/ColtPistols.aspx
Generally speaking, when you buy a Colt you (and those who value Colt's) look for sentimental value. THINK PREMIUM
AND TRADITIONAL. So don't go with base models or obscure rollmarks