AOR 2 is the acknowledgement of your application when your file is transferred to your local visa office which for pakistan is LONDON VISA OFFICE. yes every spousal immigration file is transferred to local visa office, local visa offices for different countries are different e.g., LVO( london visa office for pakistan and a few other countries )
the procedure to be completed in local visa office is the eligibility of principal applicant who is being sponsored to canada , the genuineness of marriage, and the back ground check of the applicant (security checks criminality checks etc ) and then on the basis of your application they finalize your immigration and send you PPR ( passport request ) so that they stamp your passport with the spousal visa.
here's the link to another thread on this forum where you can see the pattern for pakistani applicants whose cases are processed at LVO.
https://www.canadavisa.com/canada-immigration-discussion-board/threads/spousal-sponsorship-pakistan-london-visa-office.203899/page-3121