I saw the 55" F6300 and F6400 side by side, and the picture looked exactly the same to me, but it was at BB playing their demo. The main differences are:
- F6400 has 3D, 3DSound, and 2 pairs of glasses.
- F6400 has Micro Dimming, which I personally like.
- F6300 has a wider frame (the clear acrylic around the black bezel is thicker).
- F6400 has a black stand, the F6300's stand is silver.
- F6400 has a 480 Clear Motion Rate vs. 240 CMR on the F6300. Both are 120Hz native.
- F6400 has a Smart Touch Remote with Voice Interaction.
- F6400 has Smart View (you can watch whatever's currently on the screen on other devices like phones, pads, PC, etc.)
- F6400 has Sound Share (wireless connection with, and control of, audio devices like sound bars, home theater systems, etc.)
- F6400 supports Bluetooth for remote and other devices.
- Some of Samsung's 2013 devices (like the HW-F450 sound bar) have features that only work with an F6400 or higher TV.
So if you don't want 3D and Micro Dimming, the rest of the differences are either cosmetic (thicker frame and silver stand) or features and functions that don't really affect picture quality.