GIT FORK Forking is an operation used by GitHub to create a copy of an entire remote repository. It is primarily used to contribute to someone else's project. Changes are made locally, pushed to the forked version of the repository, then merged with the original repository after a pull request is made.
GIT CLONE Creates a local copy of a repository hosted on GitHub. It copies all of the files and branches of the remote repository.
GIT BRANCH Used to create different versions of the codebase for specific tasks (e.g. experimental, development, stable, etc.) This is done so that changes can be made to the existing code without disrupting the current working version of the code. Branching doesn't copy the codebase, it just references different commits, so it isn't a complete duplicate of the current code.