Xi'an vs Xian

Xi'an and Xian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Xi'an	Yes	No	No	No
Xian	Yes	No	No	No

As nouns, Xi'an and Xian are synonyms defined as:

Xi'an and Xian: a city of central China; capital of ancient Chinese empire 221-206 BC

Other synonyms of Xi'an include Changan, Hsian, Sian, Singan.

Xi'an (noun)	Xian (noun)
a city of central China; capital of ancient Chinese empire 221-206 BC	a city of central China; capital of ancient Chinese empire 221-206 BC