Sunspots on the actual sun are areas that are colder than the parts of the sun around them. Since they are colder, they aren't as bright since brightness is related to temperature. Sunspots on people's skin are dark patches because they were out in the sun too long. The reason these spots are dark on people's skin has nothing to do with temperature, it has more to do with how the skin reacts to sunlight. Although, the sun can get sunspots and people can get sunspots, they are completely different. They just happen to have the same name.