What is a whipple procedure and is it related to pancreaticoduodenectomy?

Same thing. A whipple procedure (pancreaticoduodenectomy) removes the head of the pancreas, the lower bile duct, gallbladder, and usually part of the stomach (and associated lymph nodes). The GI tract is the reconstructed in a variety of ways.
Same. Whipple procedure, other wise known as pancreatic- duodenectomy was devised to address tumors or disease involving the head of the pancreas and the surrounding structures such as the duodenal ampulla or distal common bile duct. First described in the 1940's as a two stage procedure by a.S. Whipple of columbia p&s. Classically, the distal portion of the stomach was removed as well but may be left.