cephalalgia vs head ache

cephalalgia and head ache both are nouns.

Word	Noun	Adjective	Verb	Adverb
cephalalgia	Yes	No	No	No
head ache	Yes	No	No	No

As nouns, cephalalgia and head ache are synonyms defined as:

cephalalgia and head ache: pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs

Other synonyms of cephalalgia include headache.

cephalalgia (noun)	head ache (noun)
pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs	pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs