How does the kitchen know a ticket came from an app and not from our own page?

On the orders board the line names the app and says the money was paid to the app. On the kitchen screen an app order that is still waiting for an answer shows Accept the order and Refuse instead of the usual Ready button, so it stands out. Once accepted it is cooked like any other ticket. Unmatched dishes keep the app's own wording until you match them under Which dish is which. The Orders from delivery apps tab in the docs describes the kitchen side.