wisent, aurochs, Bison bonasus - European bison having a smaller and higher head than the North American bison --1is a kind ofbison --1is a member of genus Bison
aurochs, urus, Bos primigenius - large recently extinct long-horned European wild ox; considered one of the ancestors of domestic cattle --2is a kind ofox, wild ox --2is a member of Bos, genus Bos