Both these tests vary in terms of difficulty. However, some consider OET an easier test. This is because it is specific to healthcare and the test-takers can make use of their healthcare knowledge, vocabulary, and experiences. IELTS, on the other hand, is not specific to the healthcare profession. So, for a healthcare professional, OET may be a bit easier, Nevertheless, OET is still an English language proficiency test and not a test of healthcare knowledge..