1 simple , only the local and remote branches with the same name will be pushed, and only the current branch will be pushed to the remote, that is, only one branch will be pushed to the remote
2 matching , it will push the matching local part to the remote part, if the local part does not have the remote part, it will not push the local part to the remote one, and push multiple branches to the remote one
3 nothing, you need some refspec parameters yourself, how to allocate, by default nothing is pushed
4 current, the local current branch is pushed to the remote. If the local branch is not remote, create a branch with the same name on the remote, and then push it, which also pushes a branch