: Nope, they're the same. The original name was Field Collapsing, : but it was changed to "Grouping" later.
Specificly: "Field Collapsing" is one type of usecase for the more general concept of "Result Grouping" (other types of result grouping are "group by query, group by function results, etc...) : But note that the functionality has changed over time, so you might : be seeing documents from different incarnations of the code. right ... there was a widely used patch that had param names that were very specific to the idea "field collapsing" that evolved heavily, hence the diff param names. -Hoss
