Coursework at the graduate level is not just different classes than the undergraduate. It is not simply more information on a particular topic. It is designed to be a qualitatively different experience.
Graduate coursework is more creative.
Students create systems that will help them to be a more effective professional. Graduate coursework is more self-directed. Graduate coursework is more rigorous. More is expected of the graduate student than of the certificate or undergraduate student. Graduate coursework is more attentive to epistemological issues.