Sights: Ameriglo GL 5517(model number was changed was previously GL-846)vs Bold, OEM plastic or standard Glock night sights, some police departments opted for standard Glock night sights on their M series issued pistols.
Trigger Bar/ Connector is nDLC coated vs plain steel on Gen5, connector is a nDLC coated dot connector, nDLC coated trigger is marked 33588.
Markings: Slide marked M, Barrel marked M or 5M on hood.
Extended Ambidextrous slide stop lever PN 33797 (19M) and extended .075 magazine catch PN 8794 standard option on both.
There are both Austrian and USA variants of both.
M pistols can be found in Black, BFG and Tan.
New Gen5 pistols have a beveled nose to match slide. Have not seen any M pistols with this change.
All other parts are identical to Gen5 pistols.