mastoid bone vs mastoid process

mastoid bone and mastoid process both are nouns.

Word	Noun	Adjective	Verb	Adverb
mastoid bone	Yes	No	No	No
mastoid process	Yes	No	No	No

As nouns, mastoid bone and mastoid process are synonyms defined as:

mastoid bone and mastoid process: process of the temporal bone behind the ear at the base of the skull

Other synonyms of mastoid bone include mastoid, mastoidal.

mastoid bone (noun)	mastoid process (noun)
process of the temporal bone behind the ear at the base of the skull	process of the temporal bone behind the ear at the base of the skull