It varies from case to case basis. Some are on par with western qualified people because of their knowledge, experience and ability while some are below par. There are some who got education from good universities in UK & US (including myself) with high CGPAs (even higher than their westerner friends)
I would still say that it depends heavily on negotiation skills, awareness about cost of living.

If world believe that any westerner is better than an Asian then we all know there are so many myths looming around and this is probably one of them. People are born genius & intelligent, yes education does help in polishing skills but you don’t have to be westerner to get quality education.

Yes, you are right that feeling of getting paid less considering you are as qualified as your peer is not a good feeling. This would rip apart your job satisfaction etc. So again, I would say that aim for something which is best for you rather than comparing with someone else.