Both tests are pretty much the same across the world. Questions papers are randomly set by Cambridge University. IDP & British Council conduct the test with same exam papers at different centers. Exam in Both centers is equally same.
I heard that the scores through IDP are better when compared to the British Council?
No. It is not right. The Examiners are trained by Cambridge University and are scrutinized every now and then so as to maintain the quality of scoring. Examiners also jump from BC to IDP or viceversa according to their comforts, so you will not find any changes in the scoring. Just go to the test center near you.