Compression socks will be tighter on your legs compared to regular socks in order to achieve a graduated compression effect.
It’s usually the tightest around your ankle, and looser as the sock rises up your leg.
Graduated compression is done to increase the circulation in your legs and feet, so there’s enough blood flow going to your heart.
They’re designed to prevent you from developing swollen ankles and feet when you’re flying, in addition to reducing the risk of you developing dangerous blood clots which can lead to DVT.