reapportionment vs apportioning

reapportionment and apportioning both are nouns.

Word	Noun	Adjective	Verb	Adverb
reapportionment	Yes	No	No	No
apportioning	Yes	No	No	No

As nouns, apportioning is a hypernym of reapportionment; that is, apportioning is a word with a broader meaning than reapportionment:

reapportionment: a new apportionment (especially a new apportionment of congressional seats in the United States on the basis of census results)
apportioning: the act of distributing by allotting or apportioning; distribution according to a plan

Other hypernyms of reapportionment include allocation, allotment, apportionment, assignation, parceling, parcelling.

reapportionment (noun)	apportioning (noun)
a new apportionment (especially a new apportionment of congressional seats in the United States on the basis of census results)	the act of distributing by allotting or apportioning; distribution according to a plan