What’s the difference between espresso and filter coffee?

Espresso is typically defined as a small-volume beverage brewed under pressure; classic definitions describe ~25–35 ml produced with hot water forced through finely ground coffee at high pressure, with short brew time.

Filter coffee is brewed at atmospheric pressure, and its quality is often discussed using brew strength (TDS) and extraction yield to target balance and clarity. Flavor-wise, espresso amplifies intensity (and textural compounds like crema), while filter tends to reveal origin character in a more transparent way.