dead weight vs encumbrance

dead weight and encumbrance both are nouns.

Word	Noun	Adjective	Verb	Adverb
dead weight	Yes	No	No	No
encumbrance	Yes	No	No	No

As nouns, encumbrance is a hypernym of dead weight; that is, encumbrance is a word with a broader meaning than dead weight:

Other hypernyms of dead weight include burden, incumbrance, load, onus.

dead weight (noun)	encumbrance (noun)
a heavy motionless weight	any obstruction that impedes or is burdensome
an oppressive encumbrance	an onerous or difficult concern
	a charge against property (as a lien or mortgage)