Graphics Card Comparisons

Solution
What are you looking to determine ?

The 750 Ti is faster than the plain 750.
The SC has a different cooler and factory OC
The FTW has some component improvements over the SC

I guess the GTX 750 cards are nice for a low power system, since they don't require a 6 pin connection to the psu. Since the FTW requires this 6 pin connection, it negates this benefit (might as well get a better performing R9 270 then).

So the best performing without requiring the 6 pin connector to the psu would be GTX 750ti SC, though you might be able to overclock any other GTX 750ti to the same levels or beyond.
 
The 750 SC is the same reference card with a better cooler, so yes you can usually get the same OC's provided you can stay within temp limits. This is not true for other brands where their factory OC'd cards have custom PCBs with better VRM,s Caps, chokes, etc. which provide the means to get higher / more stable OCs.