Unfortunately, there are differences in every aspect of a scope and its optics as one starts scaling the price levels. I wish there's a $500 scope that performs as well as a $3000 Nightforce/Schmidt and Bender or a $4500 Tangent Theta, but my experience says otherwise. I don't want to come off as a scope snob, but until you get behind and play with a higher end scope, it is hard to know what you are missing. Does one really need a $2500 Vortex Razor Gen 2 or a $3500 NightForce on an airgun to hit your target? No, you do not.
But in the PB world of ELR(Extreme Long Range) out to 2000-4000 yards, it matters. When you have the magnification cranked up and the elevation cranked to the max, the image quality between a mediocre vs high end scope becomes obvious. Tracking, low light image, mirage, chromatic aberration, contrast, lighting, etc all comes into play and adds up to make quantifiable differences between a mid vs high end scope as one scales the pricing ladder.
You might then say: "Well, i only shoot my airguns out to 200yds at most." That may be true, but airgun pellets have a very loopy trajectory, so at 150yds, you might need to crank your elevation knob 15mils or more, which affects the image quality since you are so far off optical center. But with a higher end scope, the effects are less and more importantly, you can also trust the elevation tracking.
Believe me when i say i wish there's a holy grail $500 scope that can replace my higher end scopes, because that would be awesoome and would save me a ton of money. There's a reason high end scopes hold their value in the secondary market much much better than guns/airguns.