For my money, the difference is if you set up something you could REALLY use to kill someone right outside their place of work and chant "hang ---!"
The noose on a stick in the meme could actually choke someone to death, whereas the guillotine in your image -- is that a real blade? Did you bring it to someone's house or place of work as a threat?
A difference of degree, perhaps, but a difference that marks the line between theater and threat.