allotment vs share

allotment and share both are nouns.

Word	Noun	Adjective	Verb	Adverb
allotment	Yes	No	No	No
share	Yes	No	Yes	No

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

allotment: the act of distributing by allotting or apportioning; distribution according to a plan
share: the allotment of some amount by dividing something

As nouns, share is a hypernym of allotment; that is, share is a word with a broader meaning than allotment:

allotment: a share set aside for a specific purpose
share: assets belonging to or due to or contributed by an individual person or group

Other hypernyms of allotment include part, percentage, portion.

allotment (noun)	share (noun)
the act of distributing by allotting or apportioning; distribution according to a plan	the allotment of some amount by dividing something
a share set aside for a specific purpose	the effort contributed by a person in bringing about a result
	a sharp steel wedge that cuts loose the top layer of soil
	assets belonging to or due to or contributed by an individual person or group
	any of the equal portions into which the capital stock of a corporation is divided and ownership of which is evidenced by a stock certificate

allotment (verb)	share (verb)
	communicate
	give out as one's portion or share
	have, give, or receive a share of
	use jointly or in common
	have in common