I'm sure a mil ATCO will be along in a minute, but my understanding is that what they call themselves depends on what desk they're sitting at, not what frequency they're on. Consequently you might find that usually LARS is provided by the Zone controller, but occasionally this responsibility is taken by Approach, Departure, or whatever, and that controller takes over that frequency. Remember that the VHF frequencies are usually secondary i.e. they will primarily be operating one of a number of UHF frequencies. Indeed, where I fly they have a 'gash' frequency for anything they need it for - when I come in on a PAR I first call Zone to request it, then they put me onto the gash frequency where I talk to Approach and then Talkdown without changing frequency. I only change again once I have vacated the runway (at which point last time the lady in question forgot herself and invited me to 'contact tower, stud 2', having presumably forgotten I was civilian traffic!)
Tim