GRE is designed to test the language ability of people who want to study or work where English is used as the language of communication. Over 3.5 million tests are taken each year.IELTS is designed to test the language ability of people who want to study or work where English is used as the language of communication. Over 3.5 million tests are taken each year.IELTS is designed to test the language ability of people who want to study or work where English is used as the language of communication. Over 3.5 million tests are taken each year.