Muscat and Oman vs Oman

Muscat and Oman and Oman both are nouns.

Word	Noun	Adjective	Verb	Adverb
Muscat and Oman	Yes	No	No	No
Oman	Yes	No	No	No

As nouns, Muscat and Oman and Oman are synonyms defined as:

Muscat and Oman and Oman: a strategically located monarchy on the southern and eastern coasts of the Arabian Peninsula; the economy is dominated by oil

Other synonyms of Muscat and Oman include Sultanate of Oman.

Muscat and Oman (noun)	Oman (noun)
a strategically located monarchy on the southern and eastern coasts of the Arabian Peninsula; the economy is dominated by oil	a strategically located monarchy on the southern and eastern coasts of the Arabian Peninsula; the economy is dominated by oil