CAT5e is for exterior use. It has additional insulation and is more durable for being exposed to the elements. And here’s a great example of why you should use it instead of CAT5.
A client called to investigate why their network connection from the main house to one of the out houses wasn’t working. It didn’t take long to find that part of the CAT5 cable had degraded, split and exposed the inner cables.
This cable had only been installed for a few years! As a quick fix we removed the frayed cable, replaced it with CAT5e and joined the two together with an exterior cable joint.