What does "ordered by their priority within the project" mean?

I see the API docs mention this for “Get tasks from a project” API

GET /projects/{project_gid}/tasks

Returns the compact task records for all tasks within the given project, ordered by their priority within the project. Tasks can exist in more than one project at a time.

What exactly is meant by “priority”? I doubt it’s looking at the actual Priority custom field, since most tasks/projects don’t even make use of that. Thus, what is Asana utilizing to determine the order of the tasks when outputting the list?

I see the “Get objects via typeahead” API mentions:

Resources with type task are returned with priority placed on tasks the user is following, but no guarantee on the order of those tasks.

Is the “Get tasks from a project” API doing the same, or is it ordering via some other method?

Priority within the project is the manual order as set in the Asana UI.