mastic vs filler

mastic and filler both are nouns.

Word	Noun	Adjective	Verb	Adverb
mastic	Yes	No	No	No
filler	Yes	No	No	No

As nouns, filler is a hypernym of mastic; that is, filler is a word with a broader meaning than mastic:

Other hypernyms of mastic include cement.

mastic (noun)	filler (noun)
an evergreen shrub of the Mediterranean region that is cultivated for its resin	the tobacco used to form the core of a cigar
an aromatic exudate from the mastic tree; used chiefly in varnishes	anything added to fill out a whole
a pasty cement used as an adhesive or filler	copy to fill space between more important articles in the layout of a magazine or newspaper
	100 filler equal 1 forint in Hungary
	used for filling cracks or holes in a surface