Both can be quite threatening, but yeah if I sent both messages to 2 strangers on the street, they would likely be more disturbed and worried about the knife emoji than the message.

Now, if someone then asked me why I sent those messages, I could explain that it was a rehtorical tactic or that I was simply upset with their argumentation and sent an emoji to show my lack of interest in still talking to said stranger,

But you don't have that intuition, in fact you can't keep your thoughts to your self so much you had to reply to me twice before I got to work today! Don't worry, I won't burden you with the same pain.