"CC" wrote in
:

Does anyone know what the differences are between the Beyerdynamic
DT990 and the DT990 Pro headphones?

Both DT990pro and DT990hifi are currently available as 250 Ohm models.
Previous versions were 600 Ohm. There seems to be an odd 80 Ohm version.

The pro has a longer headband that gives less pressure on the head.