Both skiing and hiking require long periods of time using your feet, which means comfort becomes a necessary part of the enjoyment level. Socks help avoid blisters, help your feet breathe, as well as cushion them against damage, and wearing the wrong sock at the wrong time can lead to discomfort and loss of enjoyment.
Ski socks are usually not as thick as hiking socks. The design and overall fit of a ski boot largely revolves around the use of proper ski socks in order to achieve the snug fit of the boot. Most hiking socks are too thick to allow for proper clamping of the ski boot, not to mention they add additional warming to the warmth layers already built into ski boots, which means they can cause your feet to sweat. Plus, thick hiking socks have a tendency to bunch up within the boot, which can cause the boot's locking mechanism to fail as well as cause discomfort.
Hiking socks are specifically built with comfort and moisture wicking in mind. Sweat in the summer can lead to blisters, while sweat in the winter can lead to wet feet, which can lead to frozen toes. There are generally two types of hiking socks sold: thick, cold-weather hiking socks and thinner, moisture-wicking socks. While the latter are generally suitable for warm-weather hiking, cold-weather hikers often wear a moisture-wicking layer under the thicker layer, in order to keep their feet both dry and warm.
While moisture-wicking socks can be used while skiing, for the most part they are reserved for hiking conditions. The main difference between ski socks and hiking socks is that ski socks are specifically built with ski-boots in mind. They are generally over-the-calf socks, while hiking socks are usually either mid-calf or ankle socks, depending on the preference of the hiker.
Comfort is one of the most important elements when it comes to enjoying hiking or skiing, and the proper type of sock can make either hobby an enjoyable experience, while the wrong type of footwear can make a person miserable. When your feet hurt, it often becomes impossible to enjoy yourself, regardless of the activity, and picking the right sock in advance ensures that comfort is the main priority, no matter which hobby you enjoy the most.