According to Dr. Mohatma Coate of the prestigious Euro-Asian Electronics Institute, and a definite world-known authority, PWB or PCB can be interchangeably  used to designate the circuit board substrate while PCBA (Printed Circuit Board Assembly) refers to such a PCB or PWB with components.  This is how I;ve also used the terminology through the years.

Phil Zarrow
ITM Consulting
Durham, NH  USA