CAT5 vs. CAT5e Speed
If you have a lot of 10-Mbps equipment, CAT5 cabling will serve your needs. It also handles 100-Mbps Fast Ethernet transmissions very well.
CAT5e is a 100-MHz standard, though cables are available with up to 350-MHz capabilities. You can expect problem-free, full-duplex, 4-pair Ethernet transmissions over your CAT5e UTP.
CAT5 vs. CAT5e Maximum Length
The maximum distance you can run CAT5 is 100 meters, the same as CAT5e. If you need longer runs, active components such as routers or extenders can be used, provided they are CAT5 or CAT5e compatible.
Conclusion: CAT5 vs. CAT5e Cable
The main differences between CAT5 and CAT5e can be found in the specifications. The performance requirements have been raised slightly in the new standard. CAT5e has stricter specifications for Power Sum Equal-Level Far-End Crosstalk (PS-ELFEXT), Near-End Crosstalk (NEXT), Attenuation and Return Loss (RL).
CAT5e has the capacity to handle bandwidth superior to that of CAT5. If you're running up against the performance limitations of a 100-Mbps network, you'll probably want to upgrade at least parts of your system to CAT5e or higher. CAT5e is backwards compatible and can be used in any application that would typically use CAT5.