Propaganda is a modern Latin word, the gerund form of propagare, meaning to spread or to propagate. Propaganda is generally an appeal to emotion, not intellect. It shares techniques with advertising and public relations, each of which can be thought of as propaganda that promotes a commercial product or shapes the perception of an organization, person, or brand. In post–World War II usage the word “propaganda” more typically refers to political or nationalist uses of these techniques or to the promotion of a set of ideas, since the term had gained a pejorative meaning.
To me the posters are a little like the pop art movement. Basic in the style, but they have an impact on the viewer. Again pop art was and is used in some cases to advertise a product. In the case of propaganda posters to influence the emotions, attitudes, opinions, and actions of specified target audiences for ideological, political or commercial purposes through the controlled transmission of one-sided messages (which may or may not be factual) via mass and direct media channels.