The United State Military consists of troops. There are basically 4 next level designations: soldiers, airmen, sailors, and Marines. The word Marine is to be capitalized in all uses. Within each of these 4 larger designations there are a variety of other designations (things like infantry and so on).
In my limited understanding, there are only two designations for Marines: 1) Marine 2) dead Marine
My understanding is that designation 2 refers to individuals who are currently unable to immediately perform the duties of a Marine.
As stated previously, I am a tri-polar pacifist, but these are matters that only require a few minutes of protocol training, and for me personally, even as a pacifist, I would prefer folks got it right.