Both IELTS and CELPIP are designed to measure the English language proficiency of test takers. IELTS is paper-based test and globally accepted while CELPIP is computer-based, specifically for Canadian permanent residency and citizenship.
CELPIP is a 3-hour continuous and automated test of four modules namely listening, reading, writing and speaking while in IELTS, the first three modules are conducted at a stretch on the same day but speaking is done on a different day. IELTS Speaking section includes a live conversation with an examiner, while during CELPIP you record your voice on the computer. CELPIP test uses Canadian speakers, while IELTS test includes native speakers from Australia, Canada, New Zealand, the UK and US in their Listening section. The writing section in IELTS is hand-written but in CELPIP, you have to type the writing tasks.
There is a computerized time checking in CELPIP and one cannot go back to the modules once attempted which is possible in IELTS, since it is paper-based.
The results take 13 calendar days for IELTS and 4 -5 calendar days for CELPIP.