PLY is a computer file format known as the Polygon File Format or the Stanford Triangle Format. It was designed to store three-dimensional data from 3D scanners. The data storage format supports a relatively simple description of a single object as a list of nominally flat polygons.
PRC (Product Representation Compact) is a 3D file format that can be used to embed 3D data in a PDF file.
This highly compressed format facilitates the storage of different representations of a 3D model. For example, you can save only a visual representation that consists of polygons (a tessellation), or you can save the model's exact geometry (B-rep data). Varying levels of compression can be applied to the 3D CAD data when it is converted to the PRC format using Adobe Acrobat 3D.