Every hornet is a wasp, but not every wasp is a hornet. A hornet is simply a larger, more aggressive kind of wasp with a sting that hurts more.
The core difference
A hornet is a specific, larger and more aggressive kind of wasp; wasp is the broader term.
- Wasp — a flying stinging insect related to bees and ants, usually slim-waisted with yellow-and-black markings: Wasps build papery nests under roof eaves.
- Hornet — a large, aggressive wasp with a painful sting: A hornet's nest hung from the eaves of the barn.
How to tell them apart
Because a hornet is a type of wasp, the relationship is one of category and subset rather than two unrelated insects: if you have identified a hornet, you have also identified a wasp, but the reverse is not true. Size and temperament are the practical giveaways, since hornets tend to be noticeably larger and more aggressive, with a sting that is correspondingly more painful.
Both words also carry figurative uses for a sharp or stinging person. Someone described as a wasp is sharp or irritable, while a hornet suggests someone who launches repeated, relentless small attacks, such as a critic who keeps stinging every new release.
