[Spexxvet]

My rant: Not every guy in a striped shirt is a referee, even if he's on the field

"Football officials are commonly referred to as referees, but each position has specific duties and a specific name: Referee, Umpire, Head linesman, Line judge, Back judge, Side judge, and Field judge. Because the referee is responsible for the general supervision of the game, the position is sometimes referred to as head referee or crew chief"

The referee is the one wearing the white hat.