Conversable is the enterprise-class, SaaS platform that will build your bot with you. They work with a lot of Fortune 500 companies (they’re behind the Whole Foods, Pizza Hut, 7-11, and Dunkin Donuts bots, among others). They go beyond Facebook Messenger, and will make sure your conversations are happening across all channels, including voice-based ones (like, for instance, OnStar).
Messenger Bots are created using the new Messenger API that allows a bot to send and receive messages. The Messenger Bots are essentially chat bots that you can talk to from the Messenger app. The conversations will of course be different than those you have with your Facebook friends. These bots are meant to help you get information for example you can ask the CNN bot to tell you give you the current headline news and it will fetch them for you.