All the organisms is classified into three domains namely Bacteria, Archaea and Eukarya. The bacterial cells don not process nucleus instead they have incipient nucleus. The archaea cells also do not have nucleus like bacteria and the cell wall is also differs from bacteria. The organisms of Eukarya cells process a nucleus. Thus, domain Eukarya includes eukaryotic organisms such as mammals and plants. Therefore, mammals and plants included in the same domain Eukarya.