Attempts to score, between 1-100, the required level of knowledge, skill, or ability that is required of an occupation. Typically Importance and Level are similar, but there are cases such as a Registered Nurse’s knowledge of medicine and dentistry. They usually require “65 out of 100” in terms of their level of knowledge, but the importance of having that knowledge is scored “91 out of 100.” They don’t need to know everything about the topic, but what they do need to know is very important to their job.
By comparing Level and Importance across all occupations, we can view similar occupations based on overlap between the two.
Source: O*NET Online