I may have already said this, but I think the simplest, most useful definition of propaganda is the substitution of labels for dialogue. If you call someone stupid, or a right winger (or left winger), and think that constitutes a full argument, then you are engaging in polemical rhetoric, which for my purposes is a type of propaganda.
The intent is to create two groups: one which is “in”, and by extension one which includes everyone who does not assent to the labels. Political correctness, as an example, is not a doctrine which permits argument. You either accept the “facts” that judging others is always wrong, that minorities cannot ever be disparaged, and that whatever your friends are angry about is something you MUST be angry about too. If you don’t do this, you are one of “them”.
The purpose of integration propaganda is to make you smug, and the purpose of agitation propaganda is to make you angry and/or resentful.
In the former case, you are told that within your group resides all the goodwill, generosity, intelligence, and every other desirable trait imaginable. Those outside your group are therefore the converse of all of this: they are hateful, selfish, stupid and all the bad stuff.
In the latter case (and obviously the two are connected, but sometimes you want people to sit down and shut up, and sometimes you want them terrorizing people in the street), your task is to portray the “good people” as under attack by the hated others, and to use the energies of anger, self defense, and resentment at the UNFAIRNESS of it all to mobilize people into whatever pathway best suits you politically.