What makes the different facial hairs, well, different?

When I did No-Shave November, I noticed that my beard hair was significantly different from mustache hair. The mustache hair was stiffer and hurt when tugged on, while the beard hairs would be softer and come out easy.

Of course, neither of them are similar to head hair, even though my beard did connect to my sideburns. I think the transition was around my jawbone.

What causes these differences between mustache, beard, and head/sideburn hair?