Although barbacoa can sometimes refer to the type of meat itself, often goat meat or lamb, the cooking method of barbacoa and birria are different. Barbacoa is slow-roasted or smoked meat, traditionally in a pit but now grills or smokers, for tender, delicious meat. Birria, on the other hand, is stewed or braised, allowing the tough cuts to simmer in a liquid to become tender over time.  Lamb barbacoa also makes amazing tacos but has a different flavor than birria.