Nizhnyaya Tunguska River vs Lower Tunguska

Nizhnyaya Tunguska River and Lower Tunguska both are nouns.

Word	Noun	Adjective	Verb	Adverb
Nizhnyaya Tunguska River	Yes	No	No	No
Lower Tunguska	Yes	No	No	No

As nouns, Nizhnyaya Tunguska River and Lower Tunguska are synonyms defined as:

Nizhnyaya Tunguska River and Lower Tunguska: a river that arises to the north of Lake Baikal and flows north and west to the Yenisei River

Other synonyms of Nizhnyaya Tunguska River include Tunguska.

Nizhnyaya Tunguska River (noun)	Lower Tunguska (noun)
a river that arises to the north of Lake Baikal and flows north and west to the Yenisei River	a river that arises to the north of Lake Baikal and flows north and west to the Yenisei River