mother country vs fatherland

mother country and fatherland both are nouns.

Word	Noun	Adjective	Verb	Adverb
mother country	Yes	No	No	No
fatherland	Yes	No	No	No

As nouns, mother country and fatherland are synonyms defined as:

Other synonyms of mother country include country of origin, homeland, motherland, native land.

mother country (noun)	fatherland (noun)
the country where you were born	the country where you were born