User blog comment:Advancedwarfighter/SAR- 21 & TAR- 21 differences/@comment-1260687-20100422124041

There are a NUMBER of cosmetic difference, and the SAR21 uses a slightly different action than the TAR21. This is in contrast to the M16 and C7, which are for all intents and purposes the same weapon, with the only differences being a shuffling around of a few design elements between variants.