Visually they are almost the same, but they have 2 main differences from each other: a size and a hive’s location.
Hornets are bigger than wasps – about 1-1.5 inches long. Wasp usually less than 1 inch. Hornet’s nests are aerial or in a protected aerial location. When wasps build nests above and below ground, hornets usually build underground nests.
These insects have the same diet; they prey on other insects and rarely are scavengers for sweets and proteins. Hornests more dangerous for people, than yellow jackets, but methods of getting rid of wasps and hornets in the house are the same.