burgrave vs military governor

burgrave and military governor both are nouns.

Word	Noun	Adjective	Verb	Adverb
burgrave	Yes	No	No	No
military governor	Yes	No	No	No

As nouns, military governor is a hypernym of burgrave; that is, military governor is a word with a broader meaning than burgrave:

burgrave: the military governor of a German town in the 12th and 13th centuries
military governor: the head of a government established by the military (as in a defeated country)

burgrave (noun)	military governor (noun)
the military governor of a German town in the 12th and 13th centuries	the head of a government established by the military (as in a defeated country)
a nobleman ruling a German castle and surrounding grounds by hereditary right