Brewed coffee != espresso. I think that might be the essential piece you are missing. Espresso is brewed at very high pressures and as a result the grind size

Brewed coffee != espresso. I think that might be the essential piece you are missing. Espresso is brewed at very high pressures and as a result the grind size and consistency has a large impact on the resulting shot. The difference is not at all subtle and is quantified by the extraction time for each shot.