Bowel and intestine are synonyms, but if you need to be talking in a medical context or in scientific writing, intestine is the better (and more formal) term to use. In my experience, more people use the term "intestine" in any situation.

Could be used interchangeably but according to my understanding the bowel is part of the digestive system. It is made up of the small bowel (small intestine) and the large bowel (large intestine). Hope I helped 😊

They're synonyms. Most people I've heard using the words will use large intestine / small intestine instead of large bowel / small bowel. As nouns there may be some medical differences, like off the top of my head I think intestines refers to the literal exit point of your stomach to your butt. Bowel would be the big/small intestine. I think for most general uses they're interchangeable. If you're a medical student, someone with a better anatomy background should correct me.

Medically speaking... BOWEL / INTESTINE = anything "past/after the pyloric sphyncter" up to your "rectum." The DUODENUM is the "first" part of the SMALL intestine. The RECTUM is the "last" part of the LARGE intestine. ANUS is just an opening to remove the waste. In disease terminology... BOTH "bowel and intestine" are used to pertain to diseases of the SMALL intestine. For example: - IBS (Irritable Bowel Syndrome) - Intestinal Lymphangiectasia - Intestinal Lymphoma etc. Diseases of the LARGE intestine are mainly called COLONIC diseases. For example: - Colorectal cancer - Ulcerative colitis - Colonic polyps etc. Sorry if I posted this in English. I just do not have the time to look at my medical Japanese dictionary. It would have been much easier for you to understand. If you need further clarification, you can message me here. Hope it helps. :)