To differentiate it from the last one which was a failure. Bing has a new algorithm and look so it deserves a new name but it, too, has failed to gain any ground.
coz thier brand live didnt work so they will try new alorgithm with a new brand name.. its a marketing strategy
When a product fails, the brand name associated with it also takes a beating in the eyes of the masses. It is therefore a marketing ploy to give a new name to the product, even if it is only an improved version of the earlier one! Regards, RightMan