In England hot dogs are usually called sausages even though there's a difference between sausage and hot dogs.
Hot dogs usually contain, pork, chicken and other meat and sausages are usually just made from meat coming from pigs.
However a lot of people in England are now calling hot dogs hot dogs instead of sausages but some people in England still may refer to a hot dog as a sausage.
A hot dog is a way of serving a sausage by the British so it can be confusing for Americans to order something such as a hot dog or sausage in England if they've never been there.