Luggage transfer in Hong Kong enroute to Canada?

This depends on the airport, in your case airports. You will be told when you check in but you could always call ahead to find out. In may cases, it will be tagged to your final destination and your bags will be labelled I2I which means International-to-International. If they are not, you will have to move them yourself.

Since your final leg is domestic, it will often happen that you must get your bags upon entry into the destination country (Vancouver inthat case), pass them through customs and then drop them at a designated bag drop-off location. You will rarely have to go back to the airline desk since that will be outside the transit area, unless you are also changing terminals too.

While I have not passed through Vancouver, I transited dozens of times though Hong Kong and I never had to do it there. Via the US, moving the bags in always necessary in Miami but not so in Atlanta, so it really varies by airport and terminal.

You must get your luggage at Vancouver as this is your first port of entry into Canada. You also must go through immigration first. Sources: http://www.cbsa-asfc.gc.ca/travel-voyage/ivc-rnc-eng.html and personal experience of landing, oh, I do not know, perhaps a billion times in Vancouver :)

As the OP asked about what happens in Hong Kong, not Vancouver, I will expand on my comment.

If the airline you are flying from Manila on has an Interline agreement with Air Canada, then it is likely your bags will get checked through to Canada.

If they do not, then you will need to go through immigration in Hong Kong, claim your bags and checkin for your Vancouver flight.

While most of the time a single ticket means checking through is possible, it is not a guarantee. A travel agent can still build a single ticket with multiple unrelated carriers, in which case throguh checking of baggage would not be possible.

The best approach is to call the airline you are leaving Manila on and ask if they can check bags through to Air Canada.