Isn’t propaganda just a form of persuasion? What about propaganda separates it from advertising or interpersonal communication?
Edit: Not all propaganda involves lying. For some reason, we seem to be more comfortable with a person lying to us than we are with viewing a propaganda poster that uses verifiable facts.
Edit 2: Another interesting note is that in some countries, propaganda is not viewed negatively like it is in English speaking countries.
Propaganda can also be a label applied to 1) true information presented in a certain way, and 2) the same types of information presented about subjects other than the government.
I’ll leave others to address point 1, but I think point 2 is interesting. Propaganda can be about economic systems, for example, such as capitalism, which exists outside the realm of government. Propaganda can be about industries, for example when the oil industry tries to mislead us about global warming. I think the common theme is that propaganda has to be about broad, powerful systems having, as you pointed out, serious consequences when they tell you something.