From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Earthlings who were animals and spoke, used weapons, expressed Human emotions, or otherwise behaved just like Humans were Animal-type (動物型, Dōbutsu-gata). Some of them had acquired unique powers, such as Oolong and Usagi Ninjinka.
The most numerous kind of Earthlings were the Human-type (人間型, Ningen-gata). They mostly had no unique powers, but there were some who had acquired exceptional abilities. Those like Bulma Brief and Dr. Brief possessed brilliant intelligence, those like Yajirobe had great battle potential, those like Uranai Baba had mysterious powers, etc.
Earthlings who did not fit into the Animal-type or Human-type were Monster-type (モンスター型, Monsutā-gata). Many had a distinctive appearance, like Bandages and Suke who Son Goku and his friends fought at Uranai Baba's Palace, and they possessed mysterious powers. Pilaf, whose true identity was unclear, was also included under Monster-type.