Hi Vaibhav.
I'm not sure why there is a discrepancy, but whereas GMAC has at times said that GMAT section scores range from 0 to 60, they actually range from 6 to 51. So, if you get all the questions correct in a section, you'll score 51.
However, that information does not mean that it's not helpful to get more questions correct. Your GMAT total score is not based on your section scores. It's based directly on your performance on the test. So, even if your section score doesn't increase because of your getting more questions correct, your total score may.
For instance, with Q50 and V40, you can score 730 or 740. You'll score 740, the higher score, if you get more questions correct.
For more on how the GMAT is scored, see this post.
How Is the GMAT Exam Scored?