Most of the time those people do not really know which is which.

That being said, the issue common with the two is if the timing goes off and the engine simply stops running i.e the crank shaft and cam shaft are out of sync.
Or a broken, cracked out bent cam/crank shaft which doesn't happen everyday.

I think i will find it rather amusing if i see a (untrained, uneducated) commercial bus driver that knows what the cam/crank shaft is and does.