Cat5 cable is broken into two separate categories: Cat5 and Cat5E cables. Cat5 has become obsolete in recent years, due to its limitations compared to Cat5E and Cat6 cables. Although the Cat5 cable can handle up to 10/100 Mbps at a 100MHz bandwidth (which was once considered quite efficient), the newer versions of Cat cables are significantly faster.
Cat5E cable (which stands for “Cat5 Enhanced”) became the standard cable about 15 years ago and offers significantly improved performance over the old Cat5 cable, including up to 10 times faster speeds and a significantly greater ability to traverse distances without being impacted by crosstalk.
Cat6 cables have been around for only a few years less than Cat5E cables. However, they have primarily been used as the backbone to networks, instead of being run to workstations themselves. The reason for this (beyond cost) is the fact that, while Cat6 cables can handle up to 10 Gigabits of data, that bandwidth is limited to 164 feet — anything beyond that will rapidly decay to only 1 Gigabit (the same as Cat5E).
Cat6A is the newest iteration and utilizes an exceptionally thick plastic casing that helps further reduce crosstalk. The biggest distinguishing difference between Cat6 and Cat6A cables is that Cat6A can maintain 10 Gigabit speeds for the full 328 feet of Ethernet cable.
Ultimately, those who want to have the most “future proofed” cable will want to go with Cat6A. However, for most resident and commercial purposes, Cat5E and Cat6 cables should be more than sufficient.