Excellent question, and since I really didn't know or didn't even even think to ask myself, I looked it up.
hive mind
a notional entity consisting of a large number of people who share their knowledge or opinions with one another, regarded as producing either uncritical conformity or collective intelligence.
"he has become one of those celebrities whose online presence has made him a favorite of the internet hive mind"
(in science fiction) a unified consciousness or intelligence formed by a number of alien individuals, the resulting consciousness typically exerting control over its constituent members.
"there is a Borg Queen who controls the hive mind"
Groupthink
is a psychological phenomenon that occurs within a group of people in which the desire for harmony or conformity in the group results in an irrational or dysfunctional decision-making outcome.
