reference design means it's as AMD/ATI designed it with the same PCB and memory configuration, same output options etc so therefore any reference bios should work with any other reference card, likewise any reference coolers, waterblocks etc would fit a reference design. Not sure how you would tell though if you didn't have a reference design card in front of you to compare it with!
If you don't get the answer in this thread, I'd make a new one with the title "Is this sapphire 7870 GHz edition a reference card" and give as much detail as possible (e.g. model number, SKU numbers and even pictures) so someone who has one can tell you.
if its this one: http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=1160&lid=1&pid=1473&leg=0
then just going by the output configuration then that looks reference but the cooler certainly isn't
Manufacturers (Sapphire, XFX, EVGA, ASUS etc) can take the reference design by ATI and improve on it, such as more dvi ports, more display ports, more memory, better coolers etc to differentiate themselves in the marketplace (otherwise they'd all be identical other than support and colour) and hopefully give a better product in doing so.