region vs territory

region and territory both are nouns.

Word	Noun	Adjective	Verb	Adverb
region	Yes	No	No	No
territory	Yes	No	No	No

As nouns, territory is a hyponym of region; that is, territory is a word with a more specific, narrower meaning than region:

region (noun)	territory (noun)
a part of an animal that has a special function or is supplied by a given artery or nerve	an area of knowledge or interest
a knowledge domain that you are interested in or are communicating about	a region marked off for administrative or other purposes
the extended spatial location of something	the geographical area under the jurisdiction of a sovereign state
a large indefinite location on the surface of the Earth
the approximate amount of something (usually used prepositionally as in `in the region of')