The odd one out is advertising, as it makes it clear (usually) that it's trying to get you to buy something. The other forms generally just present their position as the truth and leave it at that

nature of target market, and 'product.'

And change political outcome, say set up a dictatorship to "save" the nation.

Public relations build a persona. An image.

Advertising as stated, attempts to affect purchasing decisions.

They're all related as noted. But we all know the devil's in the details!

are blurred. How do I tell the difference? I consider a couple of factors: Source; who is doing the advertising/public relations/persuading, What; what are they trying to persuade me of, sell me.

Propaganda certainly includes advertising, and attempts to completely saturate public discourse to the exclusion of anything else. PR would be those paid to promote and manage the perceptions of a product/image. An ad campaign sounds like it's part of the propaganda/PR package. Maybe it's a difference of degree?