Logic Apps provide a way to simplify and implement scalable integrations and workflows in the cloud. It provides a visual designer to model and automates your process as a series of steps known as a workflow. There are many connectors across the cloud and on-premises to quickly integrate across services and protocols. A logic app begins with a trigger (like 'When an account is added to Dynamics CRM') and after firing can begin many combinations of actions, conversions, and condition logic.
API Apps:
API apps in Azure App Service offer features that make it easier to develop, host, and consume APIs in the cloud and on-premises. With API apps you get enterprise-grade security, simple access control, hybrid connectivity, automatic SDK generation, and seamless integration with Logic Apps.
Web Apps:
App Service Web Apps is a fully managed to compute platform that is optimized for hosting websites and web applications. This platform-as-a-service (PaaS) offering of Microsoft Azure lets you focus on your business logic while Azure takes care of the infrastructure to run and scale your apps.
Functions:
Azure Functions is a solution for easily running small pieces of code, or "functions," in the cloud. You can write just the code you need for the problem at hand, without worrying about a whole application or the infrastructure to run it. Functions can make development even more productive, and you can use your development languages of choice, such as C#, F#, Node.js, Python or PHP. Pay only for the time your code runs and trust Azure to scale as needed. Azure Functions lets you develop serverless applications on Microsoft Azure.
