What's the actual difference between espresso and regular coffee besides strength?

Beyond the difference in strength, the distinction between espresso and regular coffee (often called drip or brewed coffee) comes down to the mechanics of how they are made and the physical properties of the resulting liquid.

Here are the primary differences:

1. The Brewing Method

• Espresso is made using high pressure. Hot water is forced through finely-ground, tightly packed coffee at roughly 9 bars of pressure. This process takes only about 25–30 seconds.
• Regular coffee uses gravity. Hot water is poured over medium-coarse grounds in a filter and drips through them at atmospheric pressure. This process takes several minutes.

2. The Grind Size

• Espresso requires a very fine, powder-like grind. This creates significant resistance for the water, which is necessary for the pressurized extraction to work.
• Regular coffee uses a medium or coarse grind, which allows water to pass through the coffee bed easily under gravity.

3. Texture and Crema

• Espresso is characterized by "crema"—a reddish-brown, thick, foamy layer that forms on top. This is an emulsion of coffee oils and carbon dioxide gas created by the high pressure. It gives espresso a syrupy, heavy mouthfeel.
• Regular coffee does not have crema. It is generally lighter in body and clearer in appearance because the paper filters used in drip brewing remove most of the coffee oils and fine particulates.

4. Flavor Profile

• Espresso tends to be more concentrated and intense, highlighting the specific notes of the roast and the oils of the bean. Because it is extracted so quickly, the flavor profile is often more balanced and integrated.
• Regular coffee tends to be more delicate and subtle. Because the water is in contact with the grounds for a longer period, it can extract a wider spectrum of flavors, often resulting in a lighter, more transparent cup.

Are they different beans?

No. There is no such thing as an "espresso bean" by species. Any coffee bean can be brewed as espresso or drip. However, roasters often label bags as "espresso roast," which usually means they have been roasted slightly darker to better suit the rapid, pressurized extraction process.