In Pakistan IELTS is conducted by the British Council and AEO (Australian Education Office).There is no difference between British Council IELTS and AEO IELTS, you can register and take the test with either at your ease. Both sites conduct the same quality IELTS test.
AEO offices in Islamabad, Karachi and Lahore conduct IELTS tests quite frequently. You can get IELTS application form by visiting any of the AEO offices in Lahore, Karachi, and Islamabad or it can also be downloaded from ielts.org. You can visit the AEO office personally with complete application form to submit your IELTS test application. If there is no AEO office in your city applications can also be sent through Mail or Courier.
British Council offices in Islamabad, Karachi, Lahore, Peshawar, Multan and Quetta offer IELTS test on a regular basis. Before you submit your application form for an IELTS test make sure you attach a photocopy of your valid National Identity Card or Passport and two recent color(blue back ground)passport size photographs with the IELTS application form. You are also expected to write your full name and signature on the reverse of each photograph. You are supposed to paste one photograph steadily with glue and attach the other one using a paper clip to the IELTS Application form. Both photographs must be identical, colour photographs with a blue background and should not be more than six months old. Black and white photographs will not be accepted. These are the guidelines are for recommendation only. The decision to accept the photographs submitted by a candidate is at the Administrator’s discretion.
PS: Please do not ask me the difference between British Council IELTS exam and IDP (AEO) IELTS exam as there is none, all tests are marked by Cambridge University trained examiners therefore leaves no positive or negative impact on your final band score for either venue