Have a look at a website called "the Land List" (you can google it to get a quick link to it); there is more than enough information about nearly all Polaroid cameras there (except, strangely, the 600SE). I'm not sure, but think that the 440 is the last in the succession of x40 bellows pack film cameras with plastic lenses, whereas the 450 is the successor to the 250 and 350 which had much better glass lenses. With the news today about the cesser of production of Polaroid film, I would suggest getting hold of a glass lensed pack film camera as soon as possible and enjoy peel apart Polaroid photography for as long as you can until all the film is gone.
Typh