Hephaistos vs Hephaestus

Hephaistos and Hephaestus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Hephaistos	Yes	No	No	No
Hephaestus	Yes	No	No	No

As nouns, Hephaistos and Hephaestus are synonyms defined as:

Hephaistos and Hephaestus: (Greek mythology) the lame god of fire and metalworking in ancient mythology; identified with Roman Vulcan

Hephaistos (noun)	Hephaestus (noun)
(Greek mythology) the lame god of fire and metalworking in ancient mythology; identified with Roman Vulcan	(Greek mythology) the lame god of fire and metalworking in ancient mythology; identified with Roman Vulcan