Pause is not a superset of drawnow under all conditions.
In general, pause will "pause" longer than drawnow and is effectively a superset.
In some situations though, pause may not wait long enough.
For example, pause(.001) may wait for less time than drawnow.
So if you want to slow down a loop by pausing for 1 second, it will have the same effect as calling drawnow then pause.
But if you want to slow down a loop by some very small amount of time, you may need a drawnow first to be sure incoming events get flushed.