Meristems are region of cells capable of division and growth in plants. They are classified by their location in the plant.
Apical meristems are also known as primary meristems because they give rise to the primary plant body. Lateral meristems are secondary meristems because they are responsible for secondary growth, or increase in stem girth and thickness. Meristems form anew from other cells in injured tissues and are responsible for wound healing. (Britannica)