As nouns the difference between fanbase and fandom
is that fanbase is alternative form of lang=en while fandom is the fans of a sport, activity, work, person etc., taken as a group.
fandom
Noun
(
en noun)
The fans of a sport, activity, work, person etc., taken as a group.
The subculture of fans.
Synonyms
* (fans of something taken as a group) fan base, fanship
Antonyms
* (fans of something taken as a group) anti-fandom, hatedom