Tri-tip and brisket come from two different parts of a cow's body. The brisket is located under a cow's chest, while the tri-tip comes from the bottom sirloin, located towards the back. Brisket is very lean which is why it takes a much longer time to smoke. Tri-tip has a moderate amount of marbling which allows for shorter smoking time. The average weight of brisket is 12-15 lbs. The average tri-tip weighs 3-5 lbs.