Why does a hovercraft lift blade look one way, but a propeller another? The lift blade of a hovercraft looks like this:



Note the ten rectangular blades.

The blade of a propeller-craft looks this this:



Note the three, traditional airfoil-shaped blades.

Why are the two different? 

Edit: My question is different from the other question cited because it asks about both the number of blades and their shape, as well as other differences I may as of yet be unaware of.
Because lift propellors need to provide static pressure to inflate the airbag and hover. This means more fan blades to stop backflow.

The thrust propellors need to provide force which is a combination of static pressure and airflow but relies mostly on airflow. This means less fan blades to facilitate large airflow.