Unfortunately your question does not have a concise answer. 

CN purchased 3,185 of the steel 8-hatch reefers in 14 batches from 1940 to 1958.

There were many visual differences so to get an appreciation you will need to look at the article by Swain and Goslett in the RMC January 1996 issue for a list of the visual  differences.  

CP purchased 3,102 steel 8-hatch reefers in 17 batches from 1936 to 1956.

Similarly there were many visual differences. To get an appreciation you will need to look at the article by the same authors in the RMC December 1995 issue for a list of the visual  differences.  

John Riddell