It's a relationship where both people adhere to their respective roles. The role of the director of public prosecutions is to manage the PPSC. That includes making decisions regarding individual prosecutions and issuing guidelines on prosecutions in general. It is still very important, however, to keep the Attorney General abreast of important issues, so that the Attorney General can provide direction where needed.
The Attorney General is always the one to communicate with the DPP regarding a specific prosecution or category of prosecutions. That communication is always public, not confidential, so that Canadians know what's going on.