Git and GitHub are not same, they are completely different but still are made for each other. So first of all, lets talk of Git.
Git
Git is a distributed Version Control System that keeps track of all of the changes that you make to your project or files. To record the changes made to a particular file, we give commands to our computer. But those commands come from Git because Git is the one which is made to track the changes. On the other hand, what is GitHub. So now lets talk of it as well.
GitHub
Now the question comes, where are you going to store the changes and the files that git tracked. Of course, you can store them into your local computer but what if you want it to store on a server because this way, you can access your files and projects from any computer that has internet. This is where, GitHub comes into the play and it provides a database to store those files and changes. Since GitHub is made on top of Git, GitHub gives a good experience but wait, GitHub is not just a database where you can store your files, but it is platform for developers. Here many developers can work together on a single project and GitHub provides facilities like code review and issue section and a lot of other things to help developers. Also you can contribute to someone else' project if you want and also you can open an issue and ask for help to solve that issue. It is like a market place for developers where developers don't purchase but collaborate with each other. Since Git and GitHub are made for each other, they together becomes heaven for developers.
- In short you can say that most of the commanding is done by Git and a place for those commands is provided by GitHub.