What is the difference between cyclical and monthly options on U.S. stock index options?

Generally speaking, weekly options are P.M. Settlement (the last trading day is the expiration date, and the settlement value is calculated according to the underlying contract price after the close of the expiration date); monthly options are A.M. Settlement (the last trading day is the expiration date T-1, and the settlement value is calculated according to the underlying contract price after the opening of the expiration date).