Well, in the case of Singapore, A levels is what people get in Junior Colleges at the age of 18. O levels is what people get in Secondary School at the age of 16. A levels is a harder form of O levels because O levels is also what the schools see for admissions into Junior Colleges. So A levels is definately better. We have specific subjects and not like a Associates Degree which has a varity of courses and at the end of it you get your GPA. For O and A levels, We take specific subjects such as English, Additional Mathematics, Chinese, etc. And we get graded on each of the subject based on the exam.