Tibet vs Xizang

Tibet and Xizang both are nouns.

Word	Noun	Adjective	Verb	Adverb
Tibet	Yes	No	No	No
Xizang	Yes	No	No	No

As nouns, Tibet and Xizang are synonyms defined as:

Tibet and Xizang: an autonomous region of the Peoples Republic of China; located in the Himalayas

Other synonyms of Tibet include Sitsang, Thibet, Tibet Autonomous Region.

Tibet (noun)	Xizang (noun)
an autonomous region of the Peoples Republic of China; located in the Himalayas	an autonomous region of the Peoples Republic of China; located in the Himalayas