The top photo was taken from the ground up (versus the bottom one, which was taken standing tip-toe on a ladder and pointing down) and as a result the float seems a lot bigger in the top photo than it does in the other, and I think it would even if there weren't people there for size comparison.  In both photos, there are large shadowed spaces, which I like.  Both are just one part of the whole, but the top photo gives more of an idea of what the entire thing would look like. 

Which one do you like best and why? 
I really like both of these photos, but I like the top one the very best.  I know it was supposed to be a picture of the object, but I like that the float takes up one half of the photo and then you can see the bustle of the last minute changes going on on the left-hand side.  I also like that the shot catches the shadows beneath the float and how you see the close-up on the wheel and see the barn in the background.
How does this perspective change the photo?
As aforementioned, you can see the bustling on the left, which gives the photo life, but also the fact that you can see the length of it from wheel to barn makes the float seem a lot bigger than it does in other photos, like it does in real life.