head cold vs common cold

head cold and common cold both are nouns.

Word	Noun	Adjective	Verb	Adverb
head cold	Yes	No	No	No
common cold	Yes	No	No	No

As nouns, common cold is a hypernym of head cold; that is, common cold is a word with a broader meaning than head cold:

head cold: a common cold affecting the nasal passages and resulting in congestion and sneezing and headache
common cold: a mild viral infection involving the nose and respiratory passages (but not the lungs)

Other hypernyms of head cold include cold.

head cold (noun)	common cold (noun)
a common cold affecting the nasal passages and resulting in congestion and sneezing and headache	a mild viral infection involving the nose and respiratory passages (but not the lungs)