soubriquet vs byname

soubriquet and byname both are nouns.

Word	Noun	Adjective	Verb	Adverb
soubriquet	Yes	No	No	No
byname	Yes	No	No	No

As nouns, soubriquet and byname are synonyms defined as:

soubriquet and byname: a familiar name for a person (often a shortened version of a person's given name)

Other synonyms of soubriquet include cognomen, moniker, nickname, sobriquet.

soubriquet (noun)	byname (noun)
a familiar name for a person (often a shortened version of a person's given name)	a familiar name for a person (often a shortened version of a person's given name)