There were some differences between ATCs and FSOs in the late 70s. I worked with a controller in Alice tower who, one day told how he had chosen the job. When looking around, a friend had taken him to visit the centre in Darwin.
He first visited FS where the FSOs wore long white socks, shorts, buttoned shirt and tie. He next visited ATC where the staff wore thongs, shorts and Tee shirts. He applied for ATC.