Low-cut and ankle socks are the same, both terms refer to the same type of socks. These socks typically have a length up to the ankles, they may or may not cover them. This means ankle socks or low-cut socks can have varying lengths. The thing that distinguishes them from other types is the fact that they are markedly shorter than the crew socks, and they are primarily worn with sneakers, that's why they are also called sneaker socks.