What is the difference between the terms KPA and PA?
KPA stands for Key Process Area and applied to the Capability Maturity Model (CMM) that was retired years ago. This term no longer has any meaning.
PA stands for a CMMI Process Area.
KPA and PA are basically the same, but KPA is only relevant for the obsolete CMM and PA is only relevant for the current CMMI.
The CMMI Glossary defines a Process Area as a cluster of related practices in an area that, when implemented collectively, satisfy a set of goals considered important for making improvements in that area. All CMMI Process Areas are common to both the Continuous and Staged Representations.