If you were flying in a dead calm, but from the deck of an aircraft carrier that was steaming along at 20 knots resulting in a 20 knot apparent wind, it would feel exactly like flying in a 20 knot wind.
Likewise, if there was a 20 knot breeze on the ocean and that aircraft carrier you was flying your plane from was going downwind at 20 knots resulting in a apparant dead calm, it would feel exactly like you were flying in a dead calm.