it’s like asking if cumming and peeing feel the same, they are distinctly different but kinda similarish in that fluid is being moved… pooping is like just a bodily function, you push and things fall out… wipe and flush and move on… not much emotion other than relief. Getting ass fucked is completely different, it’s like having one of your most intimate areas opened up and penetrated in a way that simultaneously feels taboo but amazing at the same time. You aren’t pushing you are relaxing and there is a thing inside you hitting parts you didn’t even know you had. Your ass being stretched and held open, if you are properly relaxed it feels amazing, if you are nervous and clenching then it can be painful for both parties. If you have a prostate then getting that hit will force prostate fluid out and you won’t really cum but just sorta start leaking fluid, it’s wild. The term for this is prostate milking… Over all there is just a whole host of sensations and emotions involved in proper anal such that describing it as reverse pooping is not really accurate. Are there overlaps? Yes, but it’s still a very unique experience.