Admins must decide on the event's Registration Style. They can choose from Community or Lightning Event Styles. The Registration Style dictates whether the event acts as a microsite or an event in your Community Portal.
Simple and Conference Style Events are not supported on Lightning Community Sites.
Lightning Events standardize and improve the user experience of event registration and payment. This allows staff users to configure one or multi-page event microsites by integrating with Salesforce Lightning Community Builder.
Community Events are events with all the capabilities of a Lightning Event, but include the ability to navigate back to the Community Portal after registration. This is possible because Community Events do not take place on a separate microsite. Customers can register for a Community Event and then return to browsing the Community Portal Store, adding items to the Shopping Cart as desired. This unifies the Shopping Cart experience, allowing customers to check out once with the event registration and any other desired items.