The major skills are the ones that are expected to be used the most, as dictated by what class you are. So Warriors, for example, have a bunch of combat-related skills for their Major skills, as that's what the game expects them to use most often. If a skill doesn't fall into that group, it's considered a Minor skill.

Examples of basic skills include running; jumping; throwing; catching and striking. Complex skills are more difficult. They include complicated movements that require high levels of coordination and control.