Orange is Legendary, Pink (E-tech) is ultra rare, Purple is rare, Blue is Unique, Green and White are common and nothing special.
Borderlands uses a classification system for gear that follows the standard color-coding system for RPGs pioneered by World of Warcraft. A common (white) gun would be average, an uncommon (green) would be slightly above average, a rare (blue) would be a premium gun, a very rare (in WoW, "epic") (purple) would be a very strong gun, and legendary (orange) guns are second only to pearlescent. The rarity of each gun is indicated by color as stated on the page of each gun
Specifically referring to the first game, but hey.
ill be here 4 u eco jus lyk the mop on the commercial babby-wechina23 fighting games suck-bluerain