Details of Beatles Vinyl Master Recording BOX Set?

I just inherited a complete box set of the Beatles Master Recording LP set. I see them on eBay fairly often for which they sell at $1,000+. How do these differ from any other boxed LP set?

Clearly the Master Recordings are superior, or at least that is how I understand it, but what makes it better?
Deeper grooves, better vinyl, better recordings? What is it?

Thanks,
Dan