When production started, the hoods did not have turned down edges, although the headlight assemblies had beveled edges. Starting in late April/early May '64, the hoods were changed to have the turned down edges to fit more flush with the beveled headlight assemblies. This hood/headlight combo continued in production into Fall of '64 and phased out around October/November. It was replaced with the normal '65 style hood with front edges flat and non-beveled headlight assemblies.
Most would say, then, that the first hood was just a '65 hood, but the underside structure is different, mainly at the front bottom. The main difference is the first hood is missing the small dimples across the area where the hood pin attaches.