cephalic index vs cranial index

cephalic index and cranial index both are nouns.

Word	Noun	Adjective	Verb	Adverb
cephalic index	Yes	No	No	No
cranial index	Yes	No	No	No

As nouns, cephalic index and cranial index are synonyms defined as:

cephalic index and cranial index: ratio (in percent) of the maximum breadth to the maximum length of a skull

Other synonyms of cephalic index include breadth index.

cephalic index (noun)	cranial index (noun)
ratio (in percent) of the maximum breadth to the maximum length of a skull	ratio (in percent) of the maximum breadth to the maximum length of a skull