A sports coat is generally considered more casual, is thicker and looser, and is worn with layers of inner garments. Sports coats are also commonly worn outdoors, with sports utility. A blazer jacket fits slightly slimmer than a sports coat, it's not meant to be layered and is generally worn in semi-formal events. Lastly, a suit jacket is a formal jacket with matching trousers, usually made of a lighter, more premium material.