rhizoid vs filament

rhizoid and filament both are nouns.

Word	Noun	Adjective	Verb	Adverb
rhizoid	Yes	No	No	No
filament	Yes	No	No	No

As nouns, filament is a hypernym of rhizoid; that is, filament is a word with a broader meaning than rhizoid:

rhizoid: any of various slender filaments that function as roots in mosses and ferns and fungi etc
filament: a very slender natural or synthetic fiber

Other hypernyms of rhizoid include fibril, strand.

rhizoid (noun)	filament (noun)
any of various slender filaments that function as roots in mosses and ferns and fungi etc	a thin wire (usually tungsten) that is heated white hot by the passage of an electric current
	a threadlike structure (as a chainlike series of cells)
	the stalk of a stamen
	a very slender natural or synthetic fiber