To elucidate the molecular mechanisms underlying normal and malignant hematopoietic development, it is critical to identify developmental intermediates for each lineage downstream of hematopoietic stem cells. Recent advances in prospective isolation of hematopoietic stem and progenitor cells, and efficient xenogeneic transplantation systems have provided a detailed developmental map in both mouse and human hematopoiesis, demonstrating that surface phenotypes of mouse stem-progenitor cells and their human counterparts are considerably different. Here, we summarize the phenotype and functional properties and their differences of hematopoietic stem and progenitor cell populations between mouse and human.