Salonika vs Thessaloniki

Salonika and Thessaloniki both are nouns.

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

As nouns, Salonika and Thessaloniki are synonyms defined as:

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

Other synonyms of Salonika include Salonica, Thessalonica.

Salonika (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