The WhatsApp Business App is a free app for small businesses, allowing up to four people to respond to customer messages manually, without any API or bot integrations. In contrast, the WhatsApp Business Platform provides greater flexibility and customization for medium and large businesses, enabling them to integrate with various systems, including CRMs and bots, and have thousands of agents communicate with customers programmatically and manually. The platform also offers official business accounts, customizable notifications, and features like voice and video calls, Facebook Shops, and catalog support. However, it does not support WhatsApp Native Payments and Business Profile at this time. To use the platform, businesses can partner with Twilio, which provides onboarding support and Professional Services to help develop their WhatsApp use cases.