In some cases, there is no difference in file versions, but only in indentation, spacing, line ending or line numbers.
To patch despite those differences, it's possible to use the following two arguments :
--ignore-whitespace : It ignores whitespace differences (indentation, etc).
--fuzz 3 : the "--fuzz X" option sets the maximum fuzz factor to lines. This option only applies to context and unified diffs; it ignores up to X lines while looking for the place to install a hunk. Note that a larger fuzz factor increases the odds of making a faulty patch. The default fuzz factor is 2; there is no point to setting it to more than the number of lines of context in the diff, ordinarily 3.
Don't forget to user "--dry-run" : It'll try the patch without applying it.
Example :
patch --verbose --dry-run --ignore-whitespace --fuzz 3 < /path/to/patch.patch
More informations about Fuzz :
https://www.gnu.org/software/diffutils/manual/html_node/Inexact.html