It mostly depends on whether you are the cloudor or the cloudee. If you are consuming cloud services theoretically there isn’t much difference, but practically there is. You will likely be paying more for a private cloud (not so much because it is inherently more expensive, but because there isn’t any competition) and consuming the private cloud will generally be more secure. If you are the cloudor (the provider of the cloud service) it is working a bit against you . You are forced to have excess capacity that you must pay for in order to provide for the potential surge.