Community colleges offer Associate of Arts and Associate of Science degrees. It requires that you complete a minimum of 60 semester units (depending on your major) of general education and major classes.
A four-year college or university offers the Bachelor of Arts and Bachelor of Science degrees, which are more advanced. It requires that you complete a minimum of 120 semester units (sometimes more depending on your major) before graduating. You may complete 60 lower-division units at a community college and approximately 60 upper-division units at a university.
Lower-division courses are introductory classes. Upper-division classes generally specialize in your chosen major and are more advanced.
Community colleges do not offer upper-division classes. Usually, you must take lower-division courses before enrolling in upper-division classes.
A student's career choice may require a degree beyond the Associate of Arts, Associate of Science or Certificate completed at a community college. Generally, community colleges offer classes that are at the freshman and sophomore levels. For some careers, an associate degree is sufficient. However, other careers may require the advanced classes offered at four-year institutions.