omphalus vs bellybutton

omphalus and bellybutton both are nouns.

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

As nouns, omphalus and bellybutton are synonyms defined as:

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

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