Comparisons With The Sandwich

In the 18th century, on the rainy isle known as England, the Earl of Sandwich ordered his cook to serve him meat placed within slices of bread so that he didn’t have to abandon his duties for a meal. And so the sandwich was born. 

Why is a burger not a sandwich?

There are many subtle differences between the two (like the type of bread used and the way the bread is cut), not the least of which is the filling. A burger will always contain one or more grilled patties of ground food—meat or vegetables or faux meat—and will always be circular.