Here are the definitions, from the IPEDS glossary, of the three different institution types available to choose from in Account > General Settings > Institution Type:
A postsecondary institution that offers programs of at least 4 years duration or one that offers programs at or above the baccalaureate level. Includes schools that offer postbaccalaureate certificates only or those that offer graduate programs only. Also includes free-standing medical, law or other first-professional schools.
A postsecondary institution that offers programs of at least 2 but less than 4 years duration. Includes occupational and vocational schools with programs of at least 1800 hours and academic institutions with programs of less than 4 years. Does not include bachelor's degree-granting institutions where the baccalaureate program can be completed in 3 years.
Less than two-year institution
A postsecondary institution that offers programs of less than 2-years duration below the baccalaureate level. Includes occupational and vocational schools with programs that do not exceed 1800 contact hours.