Are OC Spray or Mace the same as Pepper Spray?

OC Spray is the same as Pepper Spray. Sometimes it is called this because the main ingredient in Pepper products is Oleoresin Capsicum. Also called OC for short. Technically, all Pepper Sprays are also OC Sprays. 

Mace is referring to a brand name, not a product. This brand also happens to make pepper spray.