cranium vs braincase

cranium and braincase both are nouns.

Word	Noun	Adjective	Verb	Adverb
cranium	Yes	No	No	No
braincase	Yes	No	No	No

As nouns, cranium and braincase are synonyms defined as:

Other synonyms of cranium include brainpan.

cranium (noun)	braincase (noun)
the part of the skull that encloses the brain	the part of the skull that encloses the brain