Drilling hammers should have a soft face, for hitting hardened tools.
Engineer hammers may be fully hard, but also have longer handles that I find makes them more difficult to control, but that's a matter of personal taste.
I hardly use anything but my CM drilling hammer at work and my Estwing drilling hammer is never far from me when Im doing some pounding at home. (snicker)
However there have been times I thought an Engineers hammer or Blacksmith hammer would have been a better tool for the job.