You can look at it, a simple loupe is enough to be able to clearly see the shape of particles. Sand particles from deserts are usually smaller and rounder, and much more uniform in size and shape. This makes the sand much more fluid. Beach sand is usually more irregular in both size and shape, giving it a more "grip". Here's a nice example of how it looks https://geology.com/stories/13/sand/
Desert sand being buffeted by the wind is rounded, whilst coastal sand has sharper edges.
How often does desert sand end up on beaches? How can one check for the sharpness of sand, are the sand piles higher? Is it more abrasive?