The key difference between short-term economy and long-term economy is price behavior. In the long run, prices are flexible and can respond to changes in supply or demand, while in the short run, many prices are sticky and fixed at a predetermined level, so item A is correct; In the long run, the money supply does not affect the real variables, and the irrelevance of this money to the real variables is called currency neutrality, while the long-term economy only considers the nominal variables without considering the real variables, so item C is correct; The long-term economy thinks that output depends on the ability of the economy to provide products and services, while the short-term economy thinks that output depends on the demand of the economy for products and services. So item d is correct; In the long run, only nominal variables, that is, variables expressed in money, are considered, but actual variables are not considered, so item B is wrong. So the answer is ACD.