K.W.
My son had night terrors at least once a month from 3 mos to about 10 months.
The difference between that and a nightmare is whether or not the child recognizes you. Also the presence of fear. A night mare is just a few tears and the baby goes back to sleep.
A night terror takes a few minutes longer to calm them down. My son was ok after hugs and his pacifier.
He would scream and shake his hands like he was cold. (I think he was reliving an emergency room visit he had at five weeks).
Don't worry too much it's normal.