Why do TF2 war paints apply differently than CS2 weapon finishes? ?

I'm a long-time CS player who just started checking out other source engine economies, and the weapon skin application system here has me totally confused. In CS, a skin is fixed to the gun model, but here it feels like you can choose when and where to apply a texture pattern using these paint cans. Can someone explain the technical difference in how wear float values work when you apply a paint to a specific weapon grade?

I'm a long-time CS player who just started checking out other source engine economies, and the weapon skin application system here has me totally confused. In CS, a skin is fixed to the gun model, but here it feels like you can choose when and where to apply a texture pattern using these paint cans. Can someone explain the technical difference in how wear float values work when you apply a paint to a specific weapon grade?