This is a difficult question because it depends on so many things. Overall, they are both equally hard. Some students may have strengths in some areas and it may suit certain tests. For example some students may find the writing exercise in GAMSAT matches their strengths. For some students, the abstract reasoning may be their strength and find Section 3 of UMAT particularly easy. Overall both are competitive tests but the cohort of people sitting the tests are different. Most people who sit the UMAT are school leavers whereas those who sit GAMSAT come from a wide range of backgrounds (new grads, postgrads, PhDs, Practicing Lawyers, Engineers, Scientists, Accountants etc). The median age of students sitting the UMAT is 18 and the median age of students sitting the GAMSAT is 25 years.