I just identified them as hornets and found out how nasty they are. My husband sprayed them. I did not want him to but now I am glad that he did.That looks like a bald faced hornet, you might check some photos online. Hornets are a kind of wasp but not all wasps are hornets. Sort of like a chicken is a bird but not all birds are chickens.
It was cool so they were not aggressive. Would not want to disturb them unknowingly.Those are what I have in my animal shelters and my experience with them is that they are not aggressive. The only time I've drawn their attention was when I was raking beneath their nest and let the rake fall against the shed wall. Then they came out and bounced off my head to warn me off.
I like them as they eat a lot of stable flies. I believe that's why we don't have a fly problem even though I have a lot of livestock 40 feet from my back door.