Picture the top of a shirt. One collar is white and stays clean all day, because the work is papers, screens and meetings. The other collar belongs to a tough work shirt, because the work is hands and machines and dust. English picked up that one small detail — the colour at the neck — and used it to name two whole worlds of work. Once you see the collar, everything the word does follows: it tells you where the work happens and what it is done with, and it says nothing at all about who matters more.