Remember the ad when one lady says 'उसकी साड़ी मेरी साड़ी से सफ़ेद कैसे ?' ..... It all starts by comparing. Comparison is the best way to find how any product/item/person stands among the rest. We all know that nobody and nothing in this world is perfect! So we can compare things and find out what is better for us.
Constant comparison makes one to seek perfection. If you are not compared to anything you won't feel the drive to become better in something. This is one aspect of comparison.
Second is that if someone is constantly compared (by others or by self) with somebody better say X then that person tends to try to become like X and if not able to achieve that the that person is susceptible to become depressed and jealous of X.
Comparison often brews jealousy.
We can compare products/items/movies to one another but not people because every individual is unique and no one in this world is perfect ! One can seek perfection but can never attain it. Even when products are launched in market they are not 100% efficient or 100% error free. So just look up to the people who are better in things than you and get inspired and not jealous that is a better way to become better :) and happy