Hey Trump,
the main difference is the pitch. In essence, how much the blades are angled. Not expressed in degrees, but in the distance the prop will travel on one rotation. I know it may be confusing, but the 9443 are 9" long and will travel 4.43" upward of rotated once. The 9450 are also 9" long and will travel 4.5". In other words, the latter will have more thrust, but at a price of battery consumption.
There is a neat trick to make your ill fitting blades fit. Ream the nut in the prop out just a little bit. I believe it is a 5/16 drill bit. It is minor, see what size it is. Don't worry, you won't hurt the threads as they are cut into the nut. If you look at the motor, the shaft is slightly wider than the hole in your props...
They both seem to be genuine DJI. Since everyone is upgrading to the 9450s, they're asking more for them now. If you need to save money, and who doesn't, go with the 9443s. almost as good...