Secretin is an enzyme formed by the upper intestinal layer and gets transported by blood to the PANCREAS which it stimulates: causing the flow of pancreatic juice, also the flow of bile and intestinal juice but to a lesser extent.
Alongside Gastrin, Secretin is one of the hormones of the Gastrointestinal tract; but their functions differ
Progesterone is a hormone released by the corpus luteum in the ovary. It plays important roles in the menstrual cycle and in maintaining the early stages of pregnancy. It may also be involved in the growth of certain cancers.