The first big distinguishing factor is that PTE is a computer based test, while IELTS is paper based. As a result, you record your voice and type your answers in PTE.
There is a speaking examiner and a writer examiner for IELTS. While all assessment is done by a software in PTE ,as a result the scoring in PTE is tricky.
Not every country has a PTE centre (50 countries worldwide), while it is very likely that you will be able to find test centres for IELTS with locations in 140 countries around the world, even in the USA.
There are only a few institutions around the world accepting PTE, while for IELTS almost all the educational institutions accept it.
In IELTS, skills are checked separately. This means listening, for example, is just testing your listening skills. On the other hand, in PTE there are many integrated questions such as listening and speaking in the speaking portion of the exam, or reading and writing in the reading part, or reading and speaking in the speaking part and so on.
In PTE, aside from the four main skills which are called ‘communicative skills’ in this test, there are six enabling skills: grammar, oral fluency, pronunciation, spelling, vocabulary, written discourse.
The PTE Academic reports an overall score, communicative skills score and enabling skills score, while IELTS reports an overall band score and skills band score. Obviously, the way the overall score is calculated in PTE is based on the test taker’s performance on all items in the test.
Depending upon the test centre, you may have the speaking test of IELTS on a different day (within a week before or after the actual test day), but for PTE you take the entire test on one day.
You may choose to take PTE seven days a week in the morning, at noon or even in the afternoon. You cannot choose your test time for IELTS. Almost always, it starts in the morning and on (a) specific weekday(s) like Saturday or Thursday.
There are 20 different question types in PTE, which is certain for each and every test. While the number of question types for IELTS differ from one test to another.
While you can book as many IELTS tests as you wish at the same time, you cannot book for a new PTE exam before having the result of the test you last took.
Unlike in IELTS, each question in the speaking and writing for PTE is timed separately, which can potentially be beneficial or challenging.