Simply git checkout have 2 uses
git checkout <existing_local_branch_name>git checkout -b <new_feature_branch_name> will create a new branch with the contents of master and switch to newly created branchYou can find more options at the official site
git clone is to fetch your repositories from the remote git server.
git checkout is to checkout your desired status of your repository (like branches or particular files).
E.g., you are currently on master branch and you want to switch into develop branch.
git checkout develop_branch
E.g., you want to checkout to a particular status of a particular file
git checkout commit_point_A -- <filename>
Here is a good reference for you to learn Git, lets you understand much more easily.
checkout can be use for many case :
1st case : switch between branch in local repository
For instance :
git checkout exists_branch_to_switch
You can also create new branch and switch out in throught this case with -b
git checkout -b new_branch_to_switch
2nd case : restore file from x rev
git checkout rev file_to_restore
...
One thing to notice is the lack of any "Copyout" within git. That's because you already have a full copy in your local repo - your local repo being a clone of your chosen upstream repo. So you have effectively a personal checkout of everything, without putting some 'lock' on those files in the reference repo.
Git provides the SHA1 hash values as the mechanism for verifying that the copy you have of a file / directory tree / commit / repo is exactly the same as that used by whoever is able to declare things as "Master" within the hierarchy of trust. This avoids all those 'locks' that cause most SCM systems to choke (with the usual problems of private copies, big merges, and no real control or management of source code ;-) !
Source: Stackoverflow.com