A Porterhouse steak and a T-bone steak are basically the same thing. The Porterhouse is just an oversized version of a T-bone steak. The USDA has regulations on the thickness of the steak in order for it to be called a Porterhouse, but it’s really only important to know that it is just a larger version.
On one side of the bone is a tenderloin steak and on the other is a top loin, which most know as the New York strip steak. With a Porterhouse the tenderloin section will be a lot thicker. With these steaks, you get the best of both worlds, they both really great on the grill.
So there you have it, the only real difference between a T-bone and Porterhouse is the size of the steak.
When you have a great steak, you need a really good knife to cut it. Check out my favorite steak knives.