Boar is also widely used for making shaving brushes and has its own following. Boar bristle is not graded as badger hair. But sometimes you can see the hairs ranked by their softness, e.g., premium, extra, best, super, etc. This is done again by the manufacturer as the hairs aren’t standardized. But it is true that different Boar brushes feel different.
What you will see occasionally is that different brushes come with different “percentage tops.” The percentage represents the amount of boar bristle hairs that are not clipped. So “90% tops” means that at least 90% of the hairs used have the full length. The higher number equals better quality and feel thus heftier price tag.
Boar hair has different characteristics compared to badger: stiffer, has white-yellow coloring (some manufacturers dye the hairs to give them more “badgery” look) and holds less water.
Pros: cheaper, higher end brushes with high “tops” percentage will split in time and will give you excellent lathering properties (clipped hair will not split). Some enjoy the more coarse feeling boar provides on your skin, and it does provide an excellent exfoliating effect.
Cons: needs to be broken in (gets softer and more pliable after some use), abrasive on your skin, needs more time to create the lather, smells (yes boar hair has a distinctive smell that will fade very very slowly)