What is an Access API app? How does it differ from the Customer support tool?

An app of type Access API lets you send automated messages using our send message API and receive users' messages on your webhook/callback URL that we receive for your WhatsApp Business API number. You can do so by integrating our APIs with your service or application.
On the other hand, the customer support tool provides you with a user interface that allows you to view and manually respond to user queries with the help of customer support agents.