country house vs dacha

country house and dacha both are nouns.

Word	Noun	Adjective	Verb	Adverb
country house	Yes	No	No	No
dacha	Yes	No	No	No

As nouns, dacha is a hyponym of country house; that is, dacha is a word with a more specific, narrower meaning than country house:

country house: a house (usually large and impressive) on an estate in the country
dacha: Russian country house

Other hyponyms of country house include chateau, shooting box, shooting lodge, summer house, villa, villa.

country house (noun)	dacha (noun)
a house (usually large and impressive) on an estate in the country	Russian country house