bowdlerisation vs expurgation

bowdlerisation and expurgation both are nouns.

Word	Noun	Adjective	Verb	Adverb
bowdlerisation	Yes	No	No	No
expurgation	Yes	No	No	No

As nouns, expurgation is a hypernym of bowdlerisation; that is, expurgation is a word with a broader meaning than bowdlerisation:

bowdlerisation: the act of deleting or modifying all passages considered to be indecent
expurgation: the deletion of objectionable parts from a literary work

Other hypernyms of bowdlerisation include castration.

bowdlerisation (noun)	expurgation (noun)
the act of deleting or modifying all passages considered to be indecent	the deletion of objectionable parts from a literary work
written material that has been bowdlerized