Pontus vs Pontos

Pontus and Pontos both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pontus	Yes	No	No	No
Pontos	Yes	No	No	No

As nouns, Pontus and Pontos are synonyms defined as:

Pontus and Pontos: (Greek mythology) ancient personification of the sea; father of Nereus

Pontus (noun)	Pontos (noun)
an ancient region of northern Asia Minor on the Black Sea; it reached its height under Mithridates VI but was later incorporated into the Roman Empire	(Greek mythology) ancient personification of the sea; father of Nereus
(Greek mythology) ancient personification of the sea; father of Nereus