If you want to check the changed files you need to take care of many small things like which will be best to use , like if you want to check which of the files changed just type
git status -- it will show the files with changes
then if you want to know what changes are to be made it can be checked in ways ,
git diff -- will show all the changes in all files
it is good only when only one file is modified
and if you want to check particular file then use
git diff