No think of it like the 3200+ XP is a barton core at 2.2GHz right, the XP-Mobiles are also barton core, but range from 1.8GHz to 2GHz. The 3200+ isn't "OC'd" per se, but it's hardwired into the CPU for a higher Vcore and FSB.
Basically if they have the same core, you can get a cheaper version and as long as your mobo has good overclockability you can OC the chip yourself to the exact specs of the higher chip and possibly further. You might think 'well then will both chips cap off at the same?' not necessarily, because they may have made the higher based CPU have a 'sturdier' architecture, but I don't know enough about the actual chip manufacturering process to give you a definitive answer