torpor vs lassitude

torpor and lassitude both are nouns.

Word	Noun	Adjective	Verb	Adverb
torpor	Yes	No	No	No
lassitude	Yes	No	No	No

As nouns, lassitude is a hyponym of torpor; that is, lassitude is a word with a more specific, narrower meaning than torpor:

torpor: a state of motor and mental inactivity with a partial suspension of sensibility
lassitude: a state of comatose torpor (as found in sleeping sickness)

Other hyponyms of torpor include hibernation, lethargy, sluggishness.

torpor (noun)	lassitude (noun)
inactivity resulting from lethargy and lack of vigor or energy	weakness characterized by a lack of vitality or energy
a state of motor and mental inactivity with a partial suspension of sensibility	a feeling of lack of interest or energy
	a state of comatose torpor (as found in sleeping sickness)