Does anyone know the difference between the Hori Fight Commander 4 and the newer Hori Fight Command?
Is it just the shape and PC support?
I have both of these, got the newer one a couple days ago.
Build quality wise they seem identical. Same plastics used, and the d-pad and buttons are essentially the same. There is a little bit more tactility in the new FC (particularly in the X/Sq/Tr/Ci buttons, the R1/R2 face buttons feel pretty similar to the FC4) but otherwise they are hard to distinguish.
The FC4 has a lock that you can disengage that will allow you to rotate the d-pad up to 20 degrees. I don't know who would use this but it is not present on the newer FC. There is also no diagonal sensitivity adjustment on the newer FC; it seems to be using the default setting compared to the FC4, but the differences weren't huge on any of the three settings of the FC4 and it is quite responsive. Molding and plastic on the d-pad is otherwise identical.
The shape is the primary difference between the two. The FC4 is molded differently on the left side compared to the right; the left side of the pad has a longer handle so that you have a better grip support if you want to use the pad with the claw hand position for the button side. Personally I think this is not ideal as it'll deprive you of access to the trigger buttons (which are highly usable compared to most pad triggers for fighting games), but it is a noticeable difference to the newer FC which is not usable with the claw position unless you place the pad in your lap.
The newer FC's shape is sort of like if the Genesis and Saturn pads had a fat baby. It's quite comfortable, though personally the grip is not quite as good as the FC4s regardless of the grip used. In particular the top R1 button is more of a reach if you are trying to use only your index finger to activate both triggers. The index finger sits more naturally square on the R2 trigger and requires a bit of hand shifting to hit R1; on the FC4, the index finger naturally lands between R1 and R2, and requires no hand shifting to hit either trigger comfortably.
Where the newer FC has an advantage though is that it has not just a PS3/PS4 toggle but a third PC toggle option, which switches the pad to XInput. This will allow it to work natively on any PC game as it can output in DirectInput (PS4 setting) or XInput (PC setting), whereas the FC4 will only output in DirectInput (requires an XInput wrapper to work on a game like SFV on PC).
Overall, I would probably recommend the FC4 over the newer FC unless you want the native XInput mode support.