territory vs marchland

territory and marchland both are nouns.

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

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

territory: a region marked off for administrative or other purposes
marchland: district consisting of the area on either side of a border or boundary of a country or an area

territory (noun)	marchland (noun)
an area of knowledge or interest	district consisting of the area on either side of a border or boundary of a country or an area
a region marked off for administrative or other purposes
the geographical area under the jurisdiction of a sovereign state