They're not the same thing but can be tightly linked. Propaganda is when say a government controls its citizens through lies spread by the media, censorship can be the step further to prevent those who don't buy the lies from exposing them, usually it's used when propaganda alone doesn't work, which is the case of people not divided in small factions fighting each other (lefties vs righties etc). Basically in the western world we have more propaganda than censorship because in "divided and conquered" contexts propaganda alone does still work; people buy the lies then fight against the neighbor ignoring the evil king so no need to make them feel more oppressed than necessary, a step that could incite revolts.