A surface represents the geometry associated with a physical part. A surface is a two-dimensional geometric entity that
may be used in automatic mesh generation.
Solids are closed volume of surfaces that can take any shape. Solids are three-dimensional entities that can be used in
automatic tetra and solid meshing.
A face is a single Non-uniform Rational B-Spline (NURBS) and is the smallest area entity. It has a separate underlying
mathematical definition, specified when it was created.
FE geometry is topology on top of mesh, meaning CAD and mesh exist as a single entity. The purpose of FE geometry
is to add vertices, edges, surfaces, and solids on FE models which have no CAD geometry.