Your knee won't be as "pointy" for obvious reasons, but the damage is still the same. It's not like the impact won't be as good if you wear knee protection. If you hit with the knee to the head, it will open cuts even if you wear braces.
Unless you wear a pillow on your knee, the difference is all in your head. Cause it'll feel like your knee doesn't do as much damage since there is some padding on it. Sort of like if you wear thin gloves. You don't hit directly with your knuckles, so it doesn't feel as hard when you hit. That's because YOU don't feel the impact as much as you would if you didn't have any gloves.