Propellers are those that take energy to push a fluid (air or water), and turbines are those generating energy from being pushed by a fluid. I'm fascinated with them, their blades, their shapes and designs. They are beautiful.
Helicopter has straight thin long blades, sometimes 2-fold or 3, and up to 8 or more. Airplane propellers are oblong and pointed and distinctively twisted. Propellers for ships have deep slants and fat blades with large surface areas. Modern electricity generating windmills (called wind turbines) are again narrow and long, invariably 3-fold, and characteristically pinpointed.
This page is a annotated photo exhibition of such twirling things. Airplane or ship propellers are often called screws by professionals, because they are like screws of air or water. There are also things that turn sideways like water wheels or water paddles as used by steamrollers. I call any such device Whirl Wheels. They are interesting from a engineering point of view (aerodynamics, hydrodynamics), but as well as esthetics.
Pushers of the sea.
Spinning frenzies in the sky.
See also: Architectural Beauties