Objective: To compare the difference in biological behaviors between two types of tumor stem cells derived from human Luminal A and HER-2-positive breast cancer. Methods: Primary breast cancer cells were isolated from specimens of Luminal A and HER-2-positive breast cancer tissues and cultured, and then the mammospheres (MSs) were obtained, which were highly enriched in tumor stem cells. MSs were dissociated into single cells (mammospheres-derived cells, MSDCs) by trypsin digestion, and then the proliferative and regenerative abilities in vitro, the proportions of ALDH1+ cell population, and the tumor formation abilities after inoculation into NOD/SCID mice were compared between MSDCs from the two types of breast cancer. Results: MSs formed in the primary cultured breast cancer cells either isolated from Luminal A or HER-2-positive breast cancer tissue. However, in HER-2-positive breast cancer, the MSs formation time was shorter and their volume was larger than those in Luminal A breast cancer. The proliferative and regenerative abilities in MSDCs from HER-2-positive breast cancer were significantly higher than those in MSDCs from Luminal A breast cancer either cultured in serum-free medium or medium containing serum, and the proportion of ALDH1+ cell population in the former was significantly higher than that in the latter (all P<0.05). The tumor formation ability of MSDCs from HER-2-positive breast cancer was stronger than that of MSDCs from Luminal A breast cancer in NOD/SCID mice. Conclusion: The tumor stem cells isolated from Luminal A and HER-2-positive breast cancer have significantly different biological behaviors. So the two types of breast cancer may originate from different tumor stem cells.