Camparision

Sapphire are an AIB (Add in board) manufacturer, very similar to XFX, ASUS, EVGA, Gigabyte ETC...

Basically ATI/nVidia design the cards then the AIB manufacturer's put a shiny sticker on the graphics card, may sometimes change the cooler or make small changes to the PCB layout.

Some of the main differences between different AIB's include

1) Warranty period/service
2)Factory overclock (may or may not apply)
3)Price
4)Custom cooling
5)Variations in PCB design (Only really important if your overclocking alot)
6)Accessories E.G Free games or cables

Have a shop around and compare whats in your price range.