What is the difference betwen a "messenger" and a "courier"

There used to be a Playstation game where you were a courier and had to deliver stuff on your bike. I can't remember what it was called but when you hit a car at speed it was quite impressive. It was hard.

I once took my PSP into work (courieriering) one day and played this whilst I was on standby for some strange reason...

Ha! I only just clocked the trispoke too!