2.40:1 to 2.35:1 = anamorphic on dvd but on blu-ray it's widescreen/blackbars???

[andyn1080]

why is it that on dvd versions of a movie like talladega nights the screen is 2.40:1 and its anamorphic wide screen (fills up my 16X9 hdtv) but the blu-ray version which is also 2.40:1 has the black bars on top.........what gives????? i also noticed this on 2.35:1..........so why is the dvd version anamophic while the bluray version is the same ratio but has the black bars on top???? i did notice though that crank is 2.35:1 and is anamophic on bluray and it does fill up the entire screen. bottom line is that i want my bluray movies all in anamophic widescreen!!! i hate those black bars!!!