The more modern stuff is returning a result like:

array(
  'data' => <list of results>,
  'cursor' => <data for getting the next or previous page of results>,
)

...and then some other calls (like diffusion.querycommits) also return additional keys.

This makes it easier for callers to paginate results. Although they could usually have figured out the right before / after cursors for results where the cursor is just an ID, some cases like Maniphest queries with a nonstandard order-by have a complex cursor that clients can't trivially compute.