On WP / Kenmore dryer doors
By 1960 or so in the U.S., Kenmore had the drop down plug door, about the size of a pizza delivery box, in all their dryers except TOL models which had a full-width drop down door.
Whirlpool at the same time had the same full-width drop down door in their best models, but a side-swing plug door in the rest. I remember in the early 90s some WP models and owned brands (such as Roper) got Kenmore's drop down plug, but not in huge quantity of models or for a long time period.
Not long later, Kenmore's drop down plug went away, and even the Kenmores had WP's side-swing plug (on the 5.9 cu. ft. models). Today, WP brands and KM share the same side-swing doors on the 5.9s, and the 6.5s. The 7.0 cu ft models and similar in both 27 and 29-inch cabinets often have the wide opening drop down door.
The difference between Kenmore's small drop down door, and WP's side swing is what John mentioned - the KM has two springs and two cables, whereas the WP has a simple metal hinge. The cables and springs are still high-volume repair parts, whereas I would doubt there is much repair work necessary on the old side swings.
My supposition is that in the Canadian production plant, greater production commonality was achieved by Kenmores having the same dryer doors as WP, so the U.S. version was never introduced in Canada. With lower output numbers in CA, a different Kenmore door was probably judged non-justifiable.
Gordon