In the post The Spirit and where it goes I talk about what it is and where it goes when leaves the body. Here I will tell you how to differentiate between Spirits and Ghosts.
1. Spirits that belong to the Other Side do not have any negative emotions or show any deformation or pain. They will give us the impression that they float instead of walking and will have abilities that ghosts will not have, including communicating telepathically without using any other faculty, which is known as infused knowledge or instant knowledge. Another way to recognize them is that they seek the way of being recognized in a familiar way and without frightening us, recreating smells, flavors or sensations that will seem pleasurable. Also one of their abilities will be that they can be in two places at the same time and another ability will be to move objects but only they will do it to be recognized not to frighten. Their greatest motivation is love.
2. Ghosts are those spirits that do not belong to the Other Side. One of the best ways to recognize them is that the vast majority do not recognize that they have died and the few who recognize it have been tied to someone, place, event or matter. Usually they will be confused, angry and even in some cases aggressive and petulant. Because they are being tied here and don't have a place they belong it would make them more visible and clear, that's why there are so many paranormal experiences. The ghosts will present emotions like pain, anger, among others and present themselves with deformations or wounds at the moment of death. Their motivation is complex because being trapped creates a distorted reality where we are the intruders. If they realize we are able to see them may cause that in many of these encounters be in a depressive, aggressive or making us feel unhappy way, although on rare occasions it may be the opposite being in a playful and friendly way.