Yes there are big price differences for paid RTW. In the sticky *A useful reference links there is a link to Wearybiztrvlr's spreadsheet which has all the price information as has been most recently posted.

Each FFP has its own award structure. Some (many?) do have RTW awards - but these are quite different to the paid RTWs (much more restrictive). What you can do on Aeroplan awards is best asked in the Air Canada Aeroplan forum.