Calcutta vs Kolkata

Calcutta and Kolkata both are nouns.

Word	Noun	Adjective	Verb	Adverb
Calcutta	Yes	No	No	No
Kolkata	Yes	No	No	No

As nouns, Calcutta and Kolkata are synonyms defined as:

Calcutta and Kolkata: the largest city in India and one of the largest cities in the world; located in eastern India; suffers from poverty and overcrowding

Calcutta (noun)	Kolkata (noun)
the largest city in India and one of the largest cities in the world; located in eastern India; suffers from poverty and overcrowding	the largest city in India and one of the largest cities in the world; located in eastern India; suffers from poverty and overcrowding