What is the term for police officers in command positions?
I have definitely heard the terms brass or top brass used in this situation in various US police tv series...
Wait'll the brass back at headquarters get a load of this!
For the US, you can use the Wikipedia Police Rank in the US page.
Generally, it appears very similar to the Army. The differences are at the lowest rank (as you pointed out), and at the highest.
They do seem to have dispensed with the (IMHO archaic class-based) officer/enlisted distinction which the US Army retains. If that's what you are looking for, you probably won't find it, since it doesn't exist.