What is the difference between IELTS and PTE exams?

Do I need to attend a coaching center to prepare for IELTS or PTE exams?

How long does it take to prepare for IELTS or PTE exams?

What is the average score required to get admission in a university through IELTS or PTE exams?

How much does it cost to take IELTS or PTE exams?

Can I retake the IELTS or PTE exams if I don't get the desired score in the first attempt?

How long are the IELTS and PTE scores valid?