Pluralistic ignorance
Pluralistic ignorance can be contrasted with the false consensus effect. In pluralistic ignorance, people privately disdain but publicly support a norm (or a belief), while the false consensus effect causes people to wrongly assume that most people think like they do, while in reality most people do not think like they do (and express the disagreement openly). For instance, pluralistic ignorance may lead a student to drink alcohol excessively because she believes that everyone else does that, while in reality everyone else also wishes they could avoid binge drinking, but no one expresses that due to the fear of being ostracized. A false consensus for the same situation would mean that the student believes that most other people do not enjoy excessive drinking, while in fact most other people do enjoy that and openly express their opinion about it.
False consensus effect
The false-consensus effect can be contrasted with pluralistic ignorance, an error in which people privately disapprove but publicly support what seems to be the majority view (regarding a norm or belief), when the majority in fact shares their (private) disapproval. While the false-consensus effect leads people to wrongly believe that the majority agrees with them (when the majority, in fact, openly disagrees with them), the pluralistic ignorance effect leads people to wrongly believe that they disagree with the majority (when the majority, in fact, covertly agrees with them). Pluralistic ignorance might, for example, lead a student to engage in binge drinking because of the mistaken belief that most other students approve of it, while in reality most other students disapprove, but behave in the same way because they share the same mistaken (but collectively self-sustaining) belief. In a parallel example of the false-consensus effect, a student who likes binge drinking would believe that a majority also likes it, while in reality most others dislike it and openly say so.