Why the salary difference

You are asking why one company is giving more (or less) than another company?  Seriously?  Salaries are not written down by the government or by God.

And 20% is not a big difference, that's to be expected between companies, in any country.

i  wanted to inquire why moh hospitals regardless of region in saudi i am applying from consistenyl provide similar salary and that salary is higher.
and on the other hand the pvt hospitals which i mentioned  and well known are offering lower salary and comparatively similar salary.
i was wondering what the reason could be. one always  thinks the salaries would be better in pvt hospitals compared to govt run hospitals which is a paradox compared to here in india.
i  think 20% is a huge difference especially if the salary is in thousands of riyals.