B757-767 diffs
Assuming its an Engineering course you are referring to, (its going back a few years and it was on the UK licensing system) but I had to attend a full B767 level 3 after I had done the B757 level 3, there were a few years in between, but it held for all Engineers doing both types.
Not sure what Transport Canada require, but I would assume they would need a full level 3 on the airframe and engine rather than just a diffs course.