When you go to a restaurant, a waiter takes your order and serves you your meal. Before leaving, the waiter brings you the bill and you give him or her the money to pay it.
If there is no waiter and you need to go to a counter to get your meal, a barista gives you the meals you have chosen. You can pay either the barista directly or you might need go to the till/register and pay the cashier.
Recommended for you: Cooking / At the Restaurant Vocabulary and Dialogs
