Yes, the chips are exactly the same hardware, it's only the softdevice that's different.
The nRF51822 comes as a blank chip from the factory, so you have to program the softdevice yourself as part of your production, while the nRF51922 comes with the S310 softdevice preprogrammed, similar to the nRF51422.
The nRF51922 have a preprogrammed softdevice, which is not available for the nRF51822. If you need ANT, you should use the nRF51922, but if you don't you should most definitely use the nRF51822.
With the nRF51822 you can also upgrade the softdevice on the chip, potentially enabling new features or support new roles. The nRF51822 must therefore be considered a much more flexible chip than the nRF51922, with which you are constrained to the softdevice that is preprogrammed.
The nRF51922 have a preprogrammed softdevice, which is not available for the nRF51822. If you need ANT, you should use the nRF51922, but if you don't you should most definitely use the nRF51822.
With the nRF51822 you can also upgrade the softdevice on the chip, potentially enabling new features or support new roles. The nRF51822 must therefore be considered a much more flexible chip than the nRF51922, with which you are constrained to the softdevice that is preprogrammed.
