
HTH:
Vomiting is the ejection of contents of the stomach and upper intestine; regurgitation is the ejection of contents of the esophagus. The esophagus is a narrow, muscular tube that food passes through on its way to the stomach. In health, food moves quickly through the esophagus to the stomach. If the muscle of the esophagus loses tone, the esophagus dilates, a condition called megaesophagus. A dilated esophagus does not effectively move food to the stomach and the animal will regurgitate food usually shortly after eating. The food may also be inhaled (aspirated) into the airways causing coughing.
~ Vomiting is an active process. The dog is apprehensive and heaves and retches to vomit. If food is present in vomit, its partially digested and a yellow liquid (sometimes with bile).
~Regurgitation is fairly passive The animal lowers its head and food is expelled without effort. The food brought up by regurgitation is usually undigested, may have a tubular shape, and is often covered with a slimy mucus. The pet will often try to eat the regurgitated material. bring a fresh sample of "vomit" for the vet to examine the pH of vomit containing food is acid, the pH of regurgitated materials is higher.
Lovely topic ;) :D