How much damage you do when you attack a monster's part is described by what players call the "Hitzone Value", or HZV for short. The higher the HZV, the more damage you do, so you want to be hitting parts with high HZVs as much as you can!
Each part has multiple HZVs though. "Raw", non-elemental damage can be affected by either the Sever, Blunt, or Shot HZV depending on the type of damage your attack does. Cutting weapons, like the Long Sword or Dual Blades, usually do Sever damage. Sever damage is the only way to cut tails! Bludgeoning weapons, like the Hammer or Hunting Horn, usually do Blunt damage, which let you knock-out the monster. Shot damage is usually done by ranged weapons, like the Bow or Heavy Bowgun.
There are exceptions, though! The Sword and Shield normally does Sever damage, but shield bashes do Blunt damage. Likewise, the Light Bowgun usually uses Shot damage, but if you use
Slicing Ammo you can do Sever damage! This can let you use a better HZV, or let you knock out a monster or cut a monster's tail when you normally couldn't!
In addition to raw HZVs, each part also has an elemental HZV, or eHZV for short. Like with raw HZV, a higher eHZV means that you'll do more element damage! Each part has a separate eHZV for each of the five elements:
Fire,
Water,
Thunder,
Ice, and
Dragon.