Civvies know of six ranks
Private, Sergeant, Captain, Colonel, General, and Admiral.
Outside of that you will have to do explaining, which really means nothing as they look at you nodding their heads smiling like they care.
That is the reality. THey don't care who you were, but what you can do for their business. Period.
I would argue that they know a few more than that.
Commander, CO, Sgt Major, master chief and Grand Moff. Oh, and science officer.