demand vs lack

demand and lack both are nouns.

Word	Noun	Adjective	Verb	Adverb
demand	Yes	No	Yes	No
lack	Yes	No	Yes	No

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

Other hyponyms of demand include deficiency, want, necessity.

demand (noun)	lack (noun)
the act of demanding	the state of needing something that is absent or unavailable
required activity
an urgent or peremptory request
the ability and desire to purchase goods and services
a condition requiring relief

demand (verb)	lack (verb)
request urgently and forcefully	be without
claim as due or just	To be insufficiently prepared
summon to court
ask to be informed of
lay legal claim to
require as useful, just, or proper