Collection
Part of speech: noun
Definition: A set of items or objects procured or gathered together by a person, group, or other agent. Multiple related objects associated as a group. The activity of collecting.
Example sentence: I have a collection of ukuleles. I meant to graduate to the guitar, but I never did.
Aggregation
Part of speech: noun
Definition: The act of collecting together (aggregating).The state of being collected into a mass, assemblage, or sum (aggregated).A collection of particulars; an aggregate.summarizing multiple routes into one route.the majority of the parasite population concentrated into a minority of the host population.