PDM (Product Data Management) and PLM (Product Lifecycle Management) are two different but related approaches to managing product data and the product lifecycle.
PDM focuses on managing product data, such as 3D models, 2D drawings, customer requirements, and so on. PLM goes beyond managing product data and also includes managing the processes and people involved in the product lifecycle, such as engineering, manufacturing, and marketing.
PDM and PLM are often used together, with PDM being used to manage the product data and PLM being used to manage the processes and people. However, it is possible to use PDM without PLM or PLM without PDM.