Horse collar vests consist of an inflatable tube that fits over the head with adjustable waist and crotch straps to hold the vest in place. These vests tend to be lightweight and easy to pack, making them a great choice if you plan on traveling with your snorkeling gear. However, they provide less protection from the elements and are usually less comfortable than jacket-style vests.
Snorkeling jackets have fabric on the back ranging from a thin mesh layer to neoprene for added warmth and protection. Some have a zipper closure on the front, while others fit over the head with a zipper, velcro, or other closure on the side. Because they offer additional support, snorkel jackets are a better choice for non-swimmers.