Plant meristem is tissue in plants containing undifferentiated cells found in zones of plants where growth take place. Meristematic plant cells give rise to various organs of plants and keep the plant growing. Plant stem cells on the other hand side are innately undifferentiated cells located in meristems of plant. Plant stem cells serve as origin of plant vitality, as they maintain themselves while providing a steady supply of precursor cells to form differentiated tissues and organs in the plants.
You can go through the following links for more differences between plant meristem and the plant stem cells.
meristematic cells are active cells - high content of cytoplasm have ability to division , however stem cells are differantiated to paraenchyma collenchyma according to tissue
i think you mean stem cell in animal which undifferantiated cells and active