Ulaanbaatar vs Ulan Bator

Ulaanbaatar and Ulan Bator both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ulaanbaatar	Yes	No	No	No
Ulan Bator	Yes	No	No	No

As nouns, Ulaanbaatar and Ulan Bator are synonyms defined as:

Other synonyms of Ulaanbaatar include capital of Mongolia, Kulun, Urga.

Ulaanbaatar (noun)	Ulan Bator (noun)
the capital and largest city of Mongolia	the capital and largest city of Mongolia