There really aren't too many practical differences.
The spurless hammer CAN still be cocked on SOME revolvers, but in the real world this isn't either practical OR safe.
Most any revolver can be converted to a spurless configuration, so this offers a MUCH wider choice in guns and calibers.
The concealed hammer guns are a little more bulky due to the shrouding.
A concealed hammer is even more snag-proof, and can be fired more reliably from inside a pocket, although again, in the real world, this is something rarely done.
Some concealed hammer guns can still be cocked for single action, but again, this is not something you'd do in a real defense situation.
There are not too many concealed hammer guns available, so choices are limited, and limited to mostly small, .38 revolvers.