omphalos vs bellybutton

omphalos and bellybutton both are nouns.

Word	Noun	Adjective	Verb	Adverb
omphalos	Yes	No	No	No
bellybutton	Yes	No	No	No

As nouns, omphalos and bellybutton are synonyms defined as:

Other synonyms of omphalos include belly button, navel, omphalus, umbilicus.

omphalos (noun)	bellybutton (noun)
a scar where the umbilical cord was attached	a scar where the umbilical cord was attached