AOR1 is the email that lets you know the application package has been received at Mississauga. It is sent to the sponsor and contains the application number and the sponsor's UCI, so they can sign into e-CAS and watch for decision made on the sponsor application. The AOR2 is supposed to be sent to the applicant following sponsor approval. It informs them of the file transfer and which visa office their application went to.
In our case, the AOR2 was actually sent to me. My husband, who is the applicant, has never been contacted by the CIC at all, everything has come to my email address. We also got the request for additional documents and the Right of Permanent Residence fee in the AOR2 email.