Madras vs Tamil Nadu

Madras and Tamil Nadu both are nouns.

Word	Noun	Adjective	Verb	Adverb
Madras	Yes	No	No	No
Tamil Nadu	Yes	No	No	No

As nouns, Madras and Tamil Nadu are synonyms defined as:

Madras and Tamil Nadu: a state in southeastern India on the Bay of Bengal (south of Andhra Pradesh); formerly Madras

Madras (noun)	Tamil Nadu (noun)
a city in Tamil Nadu on the Bay of Bengal; formerly Madras	a state in southeastern India on the Bay of Bengal (south of Andhra Pradesh); formerly Madras
a state in southeastern India on the Bay of Bengal (south of Andhra Pradesh); formerly Madras