Grouping options in the Table View are presentational, controlling user roll-up and roll-down and the functions applied to the grouped summary bar values at the top or bottom of the Table View display in ways that the casual user can interact with.

Aggregation is transformational, setting the degree of roll-up for the data in the View(s) and the aggregation functions to be applied to all other columns as part of defining an aggregated transformation of the data set.

Only advanced users will look at an aggregated view and try to 'un-roll' the granular detail by removing aggregation settings.