The former is mainly for humanities and social science and the latter, for natural science. Generally, a bachelor of science degree, for example, requires more credits in the are of the student's major than a bachelor of arts degree does. It is not unusual for students to change majors. They do not lose many credits unless their new majors is quite different from their original major, in which case some of the classes that they have taken may not meet the requirements of the new major, and it may take more than four years to graduate. Some majors emphasize practical experience in addition to classwork.
Paramedical fields require an internship.
For example, student nurses must spend a certain amount of time working in a hospital or other medical institution under supervision. Education majors must spend part of a semester student teaching. Not all courses are offered for credit. For example, many colleges offer English courses for international students, and such classes do not usually count toward graduation. Special seminars, particularly those held in the summer and often advertised in Japan, may not offer any credit.