Leningrad vs Peterburg

Leningrad and Peterburg both are nouns.

Word	Noun	Adjective	Verb	Adverb
Leningrad	Yes	No	No	No
Peterburg	Yes	No	No	No

As nouns, Leningrad and Peterburg are synonyms defined as:

Leningrad and Peterburg: a city in the European part of Russia; 2nd largest Russian city; located at the head of the Gulf of Finland; former capital of Russia

Other synonyms of Leningrad include Petrograd, Saint Petersburg, St. Petersburg.

Leningrad (noun)	Peterburg (noun)
a city in the European part of Russia; 2nd largest Russian city; located at the head of the Gulf of Finland; former capital of Russia	a city in the European part of Russia; 2nd largest Russian city; located at the head of the Gulf of Finland; former capital of Russia