ConfusedSometimes .... I had given both the exams. In my perspective I found reading bit confusing and difficult for CELPIP, whereas reading in IELTS is pretty easy.
I had fairly done well in both exams, having said that, Writing module in IELTS is pretty strict and you need to follow the standard way of writing exam.
Overall, CELPIP is better in some sense as it is computer based exam and you don't need to write it on a paper.