Not only is it more efficient to refer to the hash value because internally it only needs to work on an int instead of a string, but there’s another benefit to it.
If you use the animation’s name to play it and have a typo, the animator will simply do nothing (except writing a log message to the console).
But if you refer to it with a hash value, you will get an error instead which makes tracking down the reason why the animation didn’t play much easier to do.