Espresso most clearly names a concentrated coffee preparation produced with an espresso machine. Hot water passes through a compacted bed of grounds under pressure. The same word also appears on blend packaging and in the names of a large family of café drinks.
Those uses overlap without being identical. A bag described as an espresso roast suggests the seller's intended application; it does not establish one mandatory roast color. A latte or cappuccino adds its own milk preparation and proportions to the underlying espresso.
When buying, decide whether you are choosing beans, selecting equipment or ordering a finished drink. For beans, look for flavor and roast information. For preparation, record dose and beverage output with the machine and basket involved. For a café order, ask about the serving if the menu's terminology is unfamiliar. This is more useful than assuming every use of the word espresso promises the same size, strength or flavor.
The conversation
A good question can make a better brew.