While currently CentOS is available on for Power8, it doesn't have an optimized version and it follows it's upstream, RHEL, for all features, wich are limited.
PowerEL wants to make this process easier and more convenient providing more packages out of the box.
PowerEL uses the distro tag __pel__ and uses the same ABI as the rhel based systems, so you can use existing binaries on PowerEL.
PowerEL is a optimized version with specific cpu architecture optimzed compiled packages, so it only works on cpu's with at least this set of features available.
## Architectures ##
PowerEL supports specific CPU architectures with specific feature requirements.