Aviation is the study of

Aviation is a broad-based term that covers all aspects of mechanical flight and the management thereof

This extends to activities that happen pre-flight, for example at an airport or engineering firm, and of course during flight as a pilot or air traffic controller

Aeronautical science covers the practical theory of aeronautics and aviation, including operations, navigation, air safety and human factors

A candidate pilot is likely to study for a qualification in aeronautical science