The main difference between wasps and hornets is that wasp colonies tend to be smaller, with fewer than 100 individuals, while hornet colonies typically have many more. It is often difficult to tell the difference between these hairless, thin-bodied, bee-like insects visually.
In addition to colony size, a major difference between wasps and hornets is nest shape and placement. Wasps often build homes that are open, umbrella-shaped and suspended from solid objects in protected locations, such as the eaves that support the roof of a covered porch. Hornets, however, build large, fully enclosed nests on tree branches or in shrubs. In either case, however, when threatened, these insects guard their home fiercely and should be avoided.