accumulation vs grouping

accumulation and grouping both are nouns.

Word	Noun	Adjective	Verb	Adverb
accumulation	Yes	No	No	No
grouping	Yes	No	No	No

As nouns, grouping is a hypernym of accumulation; that is, grouping is a word with a broader meaning than accumulation:

Other hypernyms of accumulation include group.

accumulation (noun)	grouping (noun)
the act of accumulating	any number of entities (members) considered as a unit
several things grouped together or considered as a whole	the activity of putting things together in groups
(finance) profits that are not paid out as dividends but are added to the capital base of the corporation	a system for classifying things into groups
an increase by natural growth or addition