The International English Language Testing System or IELTS is an international standardized test of English language proficiency for non-native English language speakers.
IELTS is accepted by most Australian, British, Canadian, European, Irish and New Zealand academic institutions, by over 3,000 academic institutions in the United States, and by various professional organizations across the world.
TOEFL
Test of English as a Foreign Language is a standardized test to measure the English language ability of non-native speakers wishing to enroll in English-speaking universities. The test is accepted by many English-speaking academic and professional institutions. TOEFL is one of the two major English-language tests in the world, the other being the IELTS.
TOEFL scores are accepted in universities spread across 150 countries including the US, the UK, Australia, New Zealand, France, Germany, and widely accepted in Canada. Candidates should note that TOEFL is not a requisite for your country student visa but is a requirement in your university admission.
PTE
The Pearson Test of English Academic is an English language test designed to assess the readiness of non-native English speakers to participate in a university-level English language instruction program. Pearson created PTE Academic in response to demand from institutions, government and other organizations for a more accurate way of testing non – native English language students who enter the English-speaking academia world.
In short, the main difference between IELTS and PTE is that IELTS is a paper based exam, where you read and write your answers in paper, and the PTE is all computers based. In the case of IELTS the speaking part takes the form of an interview, and in the PTE you simply speak to the computer.
GRE
The Graduate Record Examinations (GRE) is a standardized test that is an admissions requirement for many graduate schools[7] in the United States and Canada.
All the top universities around the world in US, UK, Europe, Singapore and Australia accept GRE score.