They're all slightly different, yes.
Diverges are compact bikes, so the reach is not as long as in a pure road bike. I usually ignore the brands' sizing and look instead at stack and reach. I have no idea how Specialized comes up with the 61cm, for instance. Prob virtual seat tube, but I find it irrelevant.
What Specialized frame you're more familiar with? If you know the year I can tell you how they compare.