I believe if we the readers can clearly differentiate two groups then his intentions as the author hardly matter, so I think the only way to decide this argument would be to see if the origins or physiology of the two are actually any different. I could be fuzzy on the topic but I am pretty sure all of the Orcs in Middle Earth during the time of Mordor were shaped by the Dark Lord with exception of Goblins hiding in the mountains who had their own separate society.

Regardless my statement was that the Orcs without a leader just start acting like overly hungry goblins, which stands even if you think the two terms are the same.