Stag Arms uses the designation of STAG-15 and STAG-16 as rifle designations instead of AR-15 and M-16 due to them being trademarks of another manufacturer.

Side by side, the STAG-15 and the STAG-16 look quite similar, to the point that many affirm they are the same rifle with a different name.  

Nothing can be further from the truth, starting with the fact that the STAG-15, which is targeted mainly at civilian users, is a semi-automatic rifle, while the STAG-16, which is used by police and military, is a select fire rifle which can shoot in a semi-automatic mode, burst