My boss referred to my Torana as a Cortina a few times. Obviously he has no taste or interest in cars.
They do have similar history though, just different manufacturers. Both started out as Pommy 4cyl cars. Both won Bathurst multiple times under Harry Firth's influence, in fact the Corina's second "win" was alongside the Torana DNA's first class win where the HA Viva dominated Class A. Cortinas also won Bathurst 3 years in a row (63, 64, 65), something neither Monaro, Torana or Falcon managed prior to V8 Supercar- only Commodore (82, 83, 84). The only major historical difference really is although Ford planned a V8 Cortina to take on the V8 Toranas they canned the project.