UTP stands for Unshielded Twisted Pair, and STP stands for Shielded Twisted Pair. Both are types of cabling used in Cat6a wiring. UTP cables include closely twisted pairs of wires but without any additional shielding. They are less expensive and easier to work with but may be more susceptible to electromagnetic interference. On the other hand, STP cables have additional shielding to prevent interference, making them suitable for industrial environments.