A Trotter Or A Pacer?

I was wielding my macro lens, photographing insects on my car that had been covered with fine sand blown in from the Sahara, when I heard a horse approaching on the road.

Jazzy dog took off to have a bark and I turned and pressed the shutter release.

It was one of the travellers' horses pulling a light trap. I love their gait. They sort of flick their legs up. I am not a horse person, wonder if it is called trotting or pacing?