Tanya describes very clearly, many types of souls – our souls have subconscious predilections – apart from what we all have in common, namely an animal soul (desire for pleasure / fear of pain) and an intellectual soul (desire that things should make sense) there are profound differences in the make up of our animal instincts (as the Rambam writes, in the beginning of his classic yad-hachazakah, “naturally many people are to the extreme of the center, some being cheap other frivolous, some hot tempered others cool” (and he advises the middle path to be the most correct)) But obviously in our intellect there are differences – and even on a more profound level, there are unique subset categories – the Jewish soul has in addition to the human element, a strong Divine, which is why Jews display (and have) beyond human courage in sacrificing their lives for their belief in God, and generally have a tremendous need to discover truth – this is somewhat mirrored in the Caucasian population (according to sources) descendents of Eisav, who also have a very high soul level!