Well, here's how it used to be in the old days....
General Manager-The guy who runs the station. May or may not be the owner. Makes command decisions, but leaves most of the heavy lifting to others. Spends most of his time lunching with his buddies, talking on the phone, or holed up sulking in his office. Goes ballistic when the station gets one listener complaint.
Program Director-Usually hired from out-of-town. Responsible for overall sound of the station. Supervises on-air staff and often encourages jocks to do creative things on the air (as long as it doesn't offend the General Manager). Duties may or may not include bailing jocks out of jail and fending off stalkers. Often emerges from meetings with General Manager with pale, drained look on his face.
Music Director-Reads music trades, follows trends, and picks music that is played on the station. Meritorious service may earn you the title of Assistant Program Director. The added title only means 20 dollars more per week, but it does earn you a mention in Radio and Records.
Assistant Music Director-Courtesy title given to cute girl on the air staff who helps Music Director with paperwork.
Sales Manager-Always a sleazy guy. Supervises the sales staff, which usually consists of two seasoned pros along with five little blondes just out of college. Close, personal friends with every bar owner in town. Always trying to corral air talent into doing stuff behind the Program Director's back.
News Director-Uptight, old-time newsman or woman. Totally out of touch with the rest of the station. Has a wall full of state Associated Press awards going back two decades. Woe to the jock who lets the teletype paper run out.
The Air Staff-Staff usually consists of zany morning man, mellow midday guy, afternoon guy who really wants to be a morning man, smooth night jock, and bizarre overnight guy. There is also a part-time staff for the weekends. These are folks who either have real jobs during the week and do radio for "fun", or aspiring full-timers who are waiting for someone to screw up and get fired.
Then there were other assorted characters such as the receptionist, the engineer, the preacher who did the Sunday morning show, the owner's wife, the morning man's crazy ex-wife, etc. Good times, good times......