What is the difference between Poly from the Mesh object in 3ds max?
Poly structure in 3dsmax provides much more tools for modeling objects than Mesh structure. Choosing between Poly and Mesh for modeling definitely worth to choose Poly. But, nevertheless, there are tasks, where the use of Mesh more justified than Poly.
Despite the fact that Poly is essentially the evolution of Mesh, it has a number of significant differences and limitations in their work.
In the figure you can see that if you change the form of Poly-Edit object/Editable Poly rebuilds the internal edges of polygon shown by a dotted line in a way that would prevent them from crossing. And when you work with a Mesh object (Edit/Editable Mesh) rebuilding does not occur. Additional calculations resulted in Poly objects deform slower than Mesh objects.
Increase the performance of the Skin modifier if you convert base object from Editable Poly Editable Mesh, and only then apply the Skin Modifier.
When you rebuild the object MuscleStrand model you want to use the Edit Mesh modifier to avoid “jumps” the edges of the object.
Another fundamental difference between Poly and Mesh is that Mesh allows the presence of non-manifold edges. These are the edges that are common in more than two polygons.
When converting an object Mesh to Poly, which has non-manifold edges, the polygons are split as shown in the figure.