I believe the stem cells that are capable of the most limited differentiation are embryonic stem cells. Embryonic stem cells are pluripotent (meaning they are capable to grow and differentiate) stem cells derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. These stem cells are capable of growing into all derivatives of the three primary germ layers: ectoderm, endoderm and mesoderm.