These two screenshots reflect the state of each panel in the Polygon sub-object mode, and their differences get to the heart of the distinction between the two types of objects. The Editable Poly panel indicates that no "Polygons" are selected, while the Editable Mesh panel says that no "Faces" are selected (even though we are not in Face sub-object mode). Note, also, how the Editable Mesh panel contains a checkbox to "Ignore Visible Edges" and a Planar Threshold spinner. Finally, the Editable Mesh (but not the Editable Poly) panel permits you to display normals. Each one of the points is worth understanding completely if one takes modeling seriously in MAX.