"My GRE score defines me / is like measuring height"

Your GRE score is not fixed the way your height is. If it worked like height, you'd be 5'3" one day and 6'1" the next, which would be strange. GRE scores change based on preparation, strategy, and even your mindset on test day. Your score reflects your current performance level, not your permanent ability, and that's exactly why preparation works.