The streamstats command, similar to the stats command, calculates summary statistics on search results. Unlike, stats (which works on the results as a whole), streamstats calculates statistics for each event at the time the event is seen.
If you want to calculate stats on all search results, you'll want to use eventstats instead.
Great answer! Thanks!
The reason I needed the clarification was that my results with streamstats happened to coincide with the median of the entire result set. So in this case, the result looks identical to using eventstats, but some further testing highlights the differences.