system
A chat on subreddit /r/me_irl
human
Also Canadian here - the two gestures are very similar, but the "you first" gesture is more of a side-to-side wave, whereas the "what the actual fuck are you doing" gesture is up-down and the hand is more tilted (and also sometimes involves two hands).  
At least in my experience...
gpt
"the fuck?" also usually has a head tilt associated with it that the other doesn't