chancellor vs head of state

chancellor and head of state both are nouns.

Word	Noun	Adjective	Verb	Adverb
chancellor	Yes	No	No	No
head of state	Yes	No	No	No

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

chancellor: the person who is head of government (in several countries)
head of state: the chief public representative of a country who may also be the head of government

Other hypernyms of chancellor include chief of state.

chancellor (noun)	head of state (noun)
the person who is head of government (in several countries)	the chief public representative of a country who may also be the head of government
the honorary or titular head of a university