The main difference comes down to the size of the steak and how it's cut ... On a porterhouse, "The maximum width of the tenderloin must be at least 1.25 inches (3.2 cm) when measured parallel ...
The porterhouse is that beautiful cut of meat with a large, T-shaped bone in the middle—the larger side represents the strip loin and the smaller side is a portion from the tenderloin.
People often confuse T-bone and porterhouse steaks—and even experts disagree on how to distinguish the two. Both have prominent T-shaped bones and are cut from the short loin. And both actually ...