Rostov-on-Don vs Rostov na Donu

Rostov-on-Don and Rostov na Donu both are nouns.

Word	Noun	Adjective	Verb	Adverb
Rostov-on-Don	Yes	No	No	No
Rostov na Donu	Yes	No	No	No

As nouns, Rostov-on-Don and Rostov na Donu are synonyms defined as:

Rostov-on-Don and Rostov na Donu: a seaport on the Don River near the Sea of Azov in the European part of Russia

Other synonyms of Rostov-on-Don include Rostov, Rostov on Don.

Rostov-on-Don (noun)	Rostov na Donu (noun)
a seaport on the Don River near the Sea of Azov in the European part of Russia	a seaport on the Don River near the Sea of Azov in the European part of Russia