Physically they are the same unless you specifically get one of their special cooled editions like HC18, AKIMBO, ACS3 etc.
They have in the past used different BIOS to slightly up voltages to reach higher clocks, which is also how you get the stock differences in clock speeds. Just something to keep in mind.
Also, EVGA definitely tests and bins their cards, there was some pics of an EVGA tour and their lab was pretty impressive. Overall I think a small premium, maybe 5-10% is worth it for a guaranteed and warrantied 10-15% increase in clockspeed (and usually overall performance), especially when you're spending a lot to begin with.