third house vs political unit

third house and political unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
third house	Yes	No	No	No
political unit	Yes	No	No	No

As nouns, political unit is a hypernym of third house; that is, political unit is a word with a broader meaning than third house:

third house: an interest group that tries to influence legislators or bureaucrats to act in their favor, typically through lobbying
political unit: a unit with political responsibilities

Other hypernyms of third house include interest, interest group, political entity.

third house (noun)	political unit (noun)
an interest group that tries to influence legislators or bureaucrats to act in their favor, typically through lobbying	a unit with political responsibilities