Quads vs. Triangles
 
 
 

In 3ds Max, editable meshes appear to be constructed of quads, but are actually triangles.

When imported into Maya, these editable meshes appear to be triangulated from quads.

In reality, the supposedly hidden edges are exposed as what they really are: triangles. FBX does not triangulate Editable Meshes, but instead it exposes the false hidden edges as actual edges.