Salonica vs Thessaloniki

Salonica and Thessaloniki both are nouns.

Word	Noun	Adjective	Verb	Adverb
Salonica	Yes	No	No	No
Thessaloniki	Yes	No	No	No

As nouns, Salonica and Thessaloniki are synonyms defined as:

Salonica and Thessaloniki: a port city in northeastern Greece on an inlet of the Aegean Sea; second largest city of Greece

Other synonyms of Salonica include Salonika, Thessalonica.

Salonica (noun)	Thessaloniki (noun)
a port city in northeastern Greece on an inlet of the Aegean Sea; second largest city of Greece	a port city in northeastern Greece on an inlet of the Aegean Sea; second largest city of Greece