I have given both the IDP and the British Council exam.From my experience i can tell you that the British Council is better managed(Atleast in mumbai).They have the exam at three centres while IDP conducts the exam at one location and it gets really crowded.
There is a notion that it is easier to score in the IDP as compared to the British Council.I did not find that to be true.Also British Council allows you to Send your scores to five academic institutions free of charge.IDP does not provide this option.
all in all i can say that the British Council is a better bet than IDP.
basically they both are same, its just a myth that one is better than the other...i have tried both n my results were as expected...for more information you can visit ielts forum on this site..
IDP or BC ? both fees is same, markings also same, examinations facilities same,
two advantage with BC is 8)
1.very good score in IELTS, then chances of scholarships from British council
2.can send 5 score card directly to your educational institute in canada.