Potency specifies the differentiation potential of the stem cell

• Totipotent stem cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the fertilized egg (morula) are also totipotent. These cells can differentiate into embryonic and extraembryonic cell types. Only the morula's cells are totipotent, able to become all tissues and a placenta.
  
• Pluripotent, embryonic stem cells are descendants of totipotent cells. Pluripotent, embryonic stem cells originate as inner mass cells within a blastocyst. The stem cells can become any tissue in the body, excluding a placenta.
• Multipotent stem cells can produce only cells of a closely related family of cells (e.g. hematopoietic stem cells differentiate into red blood cells, white blood cells, platelets, etc.).
• Unipotent cells can produce only one cell type, but have the property of self-renewal that distinguishes them from non-stem cells.