The article discusses the advancements and challenges in the field of induced pluripotent stem cells (iPS cells) and their potential in research and therapy. The authors highlight the development of reprogramming technology, which has enabled the creation of iPS cells from somatic cells, offering new opportunities for modeling human diseases and personalized regenerative therapies. However, they also emphasize the need to evaluate whether iPS cells are equivalent to embryonic stem (ES) cells and the subtle differences between these cell types. The review covers the derivation of iPS cells, functional assessments of pluripotency, and global comparisons of gene expression, epigenetic changes, and chromatin modifications between iPS cells and ES cells. It discusses the implications of these differences for disease modeling and therapeutic applications, suggesting that while iPS cells and ES cells are functionally equivalent, they have distinct origins and modes of derivation, leading to complementary roles in research. The article also explores the medical applications of iPS cells, including disease modeling, drug screening, and cell-replacement therapy, highlighting both the potential benefits and limitations of this technology.The article discusses the advancements and challenges in the field of induced pluripotent stem cells (iPS cells) and their potential in research and therapy. The authors highlight the development of reprogramming technology, which has enabled the creation of iPS cells from somatic cells, offering new opportunities for modeling human diseases and personalized regenerative therapies. However, they also emphasize the need to evaluate whether iPS cells are equivalent to embryonic stem (ES) cells and the subtle differences between these cell types. The review covers the derivation of iPS cells, functional assessments of pluripotency, and global comparisons of gene expression, epigenetic changes, and chromatin modifications between iPS cells and ES cells. It discusses the implications of these differences for disease modeling and therapeutic applications, suggesting that while iPS cells and ES cells are functionally equivalent, they have distinct origins and modes of derivation, leading to complementary roles in research. The article also explores the medical applications of iPS cells, including disease modeling, drug screening, and cell-replacement therapy, highlighting both the potential benefits and limitations of this technology.