Is there any difference between "do not resuscitate" and "do not attempt resuscitation" orders?

NO. "do not resusitate" and "do not attempt resusitation" orders would be received by medical professionals that the patient would not want to be resusitated in the event of a cardiopulmonary arrest/event.
Usually not. Most cases they are interchangeable. Dnh (hospitalize), dni (intubate), don't (treat) are more specific variations, but dnr and dnar are the same in most settings.