Sian vs Singan

Sian and Singan both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sian	Yes	No	No	No
Singan	Yes	No	No	No

As nouns, Sian and Singan are synonyms defined as:

Sian and Singan: a city of central China; capital of ancient Chinese empire 221-206 BC

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

Sian (noun)	Singan (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