Salonika vs Salonica

Salonika and Salonica both are nouns.

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

As nouns, Salonika and Salonica are synonyms defined as:

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

Other synonyms of Salonika include Thessalonica, Thessaloniki.

Salonika (noun)	Salonica (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