First example has no modifiers - https://gyazo.com/1489f1ab4442e06179dabec5ac55d998 Second example with edit poly - https://gyazo.com/2a726b81a4264170542676036829db26
Editable Poly doesn't support certain topologies. For example a fin extruded from an edge in the middle of a surface. That fin can't be welded to the surface, the vertices have to be detached. Editable mesh however does support that. Trouble is, Editable Mesh allows you to really fuck up your model if you're not careful.…