Undergraduate degree
In the United Kingdom, a bachelor's degree is the most common type of "undergraduate degree". Some master's degrees can be undertaken immediately after finishing secondary education; however, these courses are usually extended versions of bachelor's degree programs, taking an additional year to complete. Most bachelor's degrees take three years to complete, with some notable exceptions, such as Medicine taking five years. Often students can initially enroll in a 4-year program then leave after three years and be awarded a bachelor's degree.
Diploma of Higher Education
The Diploma certifies that a student has achieved a minimum standard for 2nd Year courses in science and liberal arts. If a student is undertaking a full Bachelor of Arts, a Diploma of Higher Education marks two-thirds of their undergraduate degree. Thus allowing the British Diploma to rank ahead of the American Associate of Arts (which in American parlance is a two-year undergraduate, or half of a BA/BS). That being said, American universities generally consider UK Diplomas equivalent to a college level Associate of Arts even though a British student typically holds more credit hours (and therefore more study time) in the arts, humanities and/or sciences.