A major (also known as a major concentration or concentration) is a term most commonly applied to a program of study leading to a bachelor's degree. Community and career college programs generally do not have majors as such. Their 1- to 3-year diploma and certificate programs carry a designation, for instance Medical Lab Technician Diploma, which is much more specific than, say, Bachelor of Science or even Bachelor of Applied Health Sciences.
Often, students in a community college or career college program--sometimes all the students in the department--will take a common set of core foundational courses in the first year (or term, in the case of shorter programs) which then enables them to pursue a specialized area of study. But generally the field of study at the community or career college level is job-focused to the point where students do not take "elective" courses as they do for bachelor's degrees. Hence the designation of the diploma effectively stands in for the "major."