Azure has a DevOps suite of tools, there’s a pipeline function that can be used to create logic, just like a Logic App from the time that the code is ready to be deployed through testing suites, through a copying of files, pushing to the development environment, sending out an email, and then when that gets authorized, sending it to staging, etc. , you can create a pipeline of that. There’s also tools for agile development processes, kanban boards and other agile methods within the dev up suite as well.
GitHub is a code sharing platform and one of the biggest names in open source, they have public as well as private git repositories where developers can host and collaborate on open source projects. GitHub was acquired by Microsoft in 2018 but has been left alone mostly, except it has first party support for Azure and tools like VS Code and Visual Stuido.
GitHub Actions is a CI/CD pipeline built into GitHub that allows developers to carry out various tasks when code is checked in or on some other trigger. It can be used for running test suites, compilations, deployments etc.