The relative airflow is
defined as that air flow unaffected by the aircraft (or helicopter) and the
angle of attack is defined as the angle between the chord line of an aerofoil
and the relative airflow.
Of course the airflow is
affected by the passage of the aircraft and we must consider three dimensional flow and how it changes up wash and down wash or as you
would say for your helicopter rotor inflow.
The actual airflow is
defined as the effective airflow and we now get an effective angle of attack,
less than the angle of attack and reducing efficiency of the aerofoil section.