Since most(all?) law enforcement agencies are organized along a para-military or semi-military structure it is relatively simple for anyone already trained in military protocols to make the transition from one to the other.
in the army there are 2 main types military police(MP) and Criminal Investigations(CID). MPs are the main force while CID do the more in depth complex investigations that require the extra time and...
Uniformed law enforcement agencies are paramilitary organizations, and generally favor their officers to have military bearing or "command presence." Some are better and/or more attentive to that...
Military police officers wear military uniforms. Added: Displayed on their military uniforms are badges, similar to civilian police badges, and/or they wear armbands or, sometimes, distinctive hats...