Stem cells are broadly categorized into embryonic stem cells (ESCs) and adult stem cells (ASCs), each with unique characteristics. ESCs, derived from the inner cell mass of embryos, are pluripotent, while ASCs, found in adult tissues, have limited differentiation potential. ASCs are preferred in stem cell therapy due to easier extraction and lower ethical concerns. However, ESCs pose ethical and safety issues, including tumor formation, leading many countries to prohibit their use in therapy.