First, a cut of beef whether a steak or a roast is a muscle. With rare exception, a roast and a steak can come from the same muscle. Some cuts of beef are tough and some are tender. Some are more tasty than others. While taste is often subjective, generally the more fat marbling a cut of beef has, the better the taste. Degrees of tenderness or toughness are mostly dependent upon the amount of exercise a particular muscle gets while the animal is alive.
What is a steak? Essentially a steak is just a slice of roast. By most definition, a steak is any piece of beef that is described as “fast-cooking” by grilling, broiling or frying. Some steaks include bone while others are boneless. Steaks are typically intended to be eaten by one person although larger steaks can be shared.
What is a roast? A roast describes a piece of meat intended to be cooked as a whole to serve more than one person. By definition a roast is most often roasted in an oven. Obviously it means slow-roasting since the roast is a larger, thicker piece of meat than a steak. Higher quality roasts (tender) can be dry oven-cooked while less quality roasts (tougher) require wet or braise cooking to make the meat more tender. Generally the slower a roast is roasted or braised, the more tender it will be.
Example of Steak Versus A Roast. A prime rib roast which comes from the rib section of a beef is a roast combined of a number of ribs cut as a whole. When sliced individually between each rib, it becomes a “ribeye steak“. The prime rib roasted is slow-roasted, The ribeye steak is either grilled or broiled which is called “dry fast cooked”.
Another example would be a tenderloin filet steak versus a tenderloin roast. You might say that the only differences between a steak and a roast comes down to size which dictates method of cooking as well as a factor of required cooking time.