Each of those versions has a different internal route/connection.
For the non-RF pad version, pin 36 is not connected, rather the antenna is either routed to the board for the uFL antenna or PCB antenna.
Bottom line, they are not interchangeable...at least not without modifying to route your own RF line back and forth. Additionally, check the XBee Reference documentation regarding PCB design, as each require unique design considerations to support the highest quality signal.