How is espresso different from coffee?

Espresso is much more intense. Espresso is not coffee, according to the definitions by the Specialty Coffee Association of America. Espresso is coffee diluted with about one to three times its weight in water and then forced through finely ground coffee at over 19 atmospheres of pressure. The resulting beverage is something between a true brewed coffee and an instant-coffee extraction; it usually contains less than 1 percent milk solids, versus greater than 10% for brewed or instant coffees. Although espresso can be made from many different roasts and beans, dark roasts with robusta beans make the strongest tasting espresso because these provide more soluble flavor oils (diterpenes).