Opening a tab in Tables app  involves opening a Seating Group and potentially swiping a card to add the customer’s name to the order. The card is not preauthorized for any amount.
Opening a tab in Authorizations app  or Bar Tabs Auths app  involves first entering an amount and then swiping a card to preauthorize that amount.
Reference Site: https://help.clover.com/faq/what-is-the-difference-between-opening-a-tab-in-tables-app-vs-opening-a-tab-in-authorizations-app-or-bar-tabs-auth-app/