filament vs filum

filament and filum both are nouns.

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

As nouns, filament and filum are synonyms defined as:

filament and filum: a threadlike structure (as a chainlike series of cells)

filament (noun)	filum (noun)
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)
a threadlike structure (as a chainlike series of cells)
the stalk of a stamen
a very slender natural or synthetic fiber