cranium vs brainpan

cranium and brainpan both are nouns.

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

As nouns, cranium and brainpan are synonyms defined as:

Other synonyms of cranium include braincase.

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