That doesn’t sound right either, what’s the difference in acceleration for an apple in atmosphere vs an apple in vacuum over 4ft of drop?

air resistance.. ?

My question is what is the actual difference, an apple isn’t going to achieve a significantly higher velocity over 4ft without air resistance

does the air resistance depend on the mass?

Drag force depends on the density of the air, the air's viscosity and compressibility, the velocity of the apple, the size and shape of the apple and the angle between the apple and the air flow.

Funny enough, since Newton's law is m z̈ = ∑ F, the actual velocity of the apple (ż) depends on the mass of the apple after all.

For the approximate force due to gravity, you have m g where g is the acceleration due to the Earth's gravity on objects close to the surface of the Earth.

In total, m z̈ = C ρ A ż^2/2 - m g where C is the drag coefficient, A is the reference area of the apple and ρ is the density of the (assumed spherical) apple.

No.

The (negligible) acceleration resulting from that air resistance (force) will depend on the mass.