I saw the Pheonix and Nightwing on the pages at forgeworld [bad painting by the way ;]. They seem to have the same weapons and even nearly the same front-part.
Because I don't have ANY of the "IMPERIAL ARMOUR"-books and only wanna buy the needed one [the pheonix needs the "UPDATE" and the Nightwing "I A 2", I ask, where the differences between both flyers are. The Pheonix a bit looks bigger, but costs the same amount of money, so I would like to buy that one, but if the rules are also nearly the same and only it's point-costs where bigger, it would be an unprofitable investigation and the Nightwing would be better. Right?

So can anyone tell me, what are the main differences?