PBA stands for "Printed Board Assembly". This number is a unique code used to identify a printed board assembly.
AA stands for "Altered Assembly". This number is a 9-digit Intel part number used to differentiate between desktop board families.
The AXXRAKSW5 is neither a printed board or a desktop board family device.
A number you might find useful is the TA number. TA stands for "Top Assembly". This number is a unique code used to identify a packaged product. This describes the AXXRAKSW5. The TA for the AXXRAKSW5 is available on a label on the package.
FYI, the TA for the AXXRAKSW5 is D42761-002.