А что сложнее сдавать TOEFL или IELTS?

Есть свои плюсы и минусы. .
В целом различие в том, что TOEFL это американский английский, а IELTS - британский
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British versus American English
While both the UK and the US accept both tests, and while British English and American English are not as different as some think, the fact of the matter is the IELTS tends to use British English and the TOEFL uses exclusively American English. On the IELTS, this difference will have a larger effect because spelling counts, and that is one area where Britain and the US do not always see eye-to-eye. Obviously if you have problems with the British accent (and the test may include a wide variety of accents, including Australian, New Zealand, Irish and Scottish). On the other hand, American accents may throw you off. Certain terms are also different and you don't want to waste time in your speaking test asking what a flat or a lorry is. So whether you are used to British or American English is certainly a factor. If you are more comfortable with US English, the TOEFL is a good bet but if you are used to British English and accents, you'll do better on the IELTS.

Multiple choice versus Copying Down
For the reading and listening sections, TOEFL gives you multiple-choice questions, whereas IELTS generally expects you to copy down words from the text or the conversation word-for-word. Multiple-choice questions will tend to be require slightly better abstract thinking, but the IELTS favors people who have good memories and think more concretely. The good thing about multiple-choice is that it is easy to pick out wrong answers, whereas the good thing about copying down is that the answer is sitting there in the text. You just have to find it and repeat it. So, concrete thinkers will tend to do better on the IELTS and abstract thinkers will tend to excel on the TOEFL.

Predictable or Different Every Time
Of course, the TOEFL is also more predictable than the IELTS. The IELTS throws lots of different question types at you, and the instructions are often slightly different every time. That makes it harder to prepare for. The TOEFL, on the other hand, is pretty much the same test every time--pick A, B, C, D, or E. On the other hand, the IELTS certainly keeps you on your toes and that can keep you more alert.

Speaking to a Person or a Computer?
Another large difference is in how the speaking section is carried out. For some people, it's very relaxing to just record your answers into a computer because it feels like no one is listening. You just try your best and forget about it until you get your grades. Because the IELTS test is done in an interview format with a native speaker present, you might get nervous or feel you are being judged. And they take notes: Oh God, did he write down something good or something bad? On the other hand, you might feel more relaxed in a conversation, with a person there to explain if you don't understand a question, or simply having a face to look at, instead of a computer screen. Getting feedback from a native speaker can be helpful too, in order to correct mistakes and improve during the test. So it depends on what you are more comfortable with. If you like talking to people, the IELTS is a better bet. If you just want to be alone and not feel judged, the TOEFL will be more comfortable for you.

Holistic versus Criteria
Finally, the speaking and writing sections of the TOEFL are graded holistically. The grader gives you a score based on the overall quality of the essay, including vocabulary, logic, style, and grammar. The IELTS by contrast is marked by individual criteria and you are scored individually for grammar, word choice, fluency, logic, cohesion, and a dozen other criteria. In other words, if you write well but have a lot of small grammar mistakes, your TOEFL score might be quite good because graders will ignore small mistakes if the overall essay is logical and detailed.

IELTS сдавать круче, однозначно. Сложней, дороже и надольше. Только это для чего Вам нужно. В подавляющем большинстве случаев TOEFL достаточно.

Вот тут подробное видео в чем разница между IELTS и TOEFL! Они же, кстати, готовят к этим тестам!
https://www.youtube.com/watch?v=jTFzdMZxTWs