Sometimes, Wikipedia is your friend:

"The strip steak is a type of cut of beef steaks. Internationally it is
called a club steak. In the United States and Canada it is also known as
New York strip, strip loin, shell steak, or Kansas City strip steak. In
Australia it is known as a porterhouse steak or boneless sirloin. Cut
from the short loin, the strip steak consists of a muscle that does
little work, and so it is particularly tender,[1] although not so tender
as the nearby rib eye or tenderloin (fat content of the strip is
somewhere between these two cuts). Unlike the nearby tenderloin, the
short loin is a sizable muscle, allowing it to be cut into the larger
portions.
When still attached to the bone, and with a piece of the tenderloin also
included, the strip steak becomes a T-bone steak or a Porterhouse steak,
the difference being that the Porterhouse has a larger portion of
tenderloin included. The strip steak may be sold with or without the
bone. Strip steaks may be substituted for most recipes calling for
T-bone and porterhouse steaks, and sometimes for fillet and rib eye steaks."

-- Larry