All big retailers advertise and many of them (if not most) often refer to holiday shopping. Christmas shopping is a term I don't recall hearing or seeing much in the media anymore, but is still widely used privately. In regards to decorating there is a distinction between low-key cardboard holiday signage with some advertisement or slogan and more recognizable decorations such as garland, wreaths, tinsel, bows and ribbons and other holiday centric items and images. Snowmen, Santa and reindeer are also Christmas decorations and where Santa has rather tangental religious connections.Best Buy always decorates during the holidays, but I can't remember if they do Christmas decorations or if they stick with more general winter themes. I'm pretty sure they have Christmas commercials, though.
If BestBuy is allowing decorations (and even Christmas Trees?) in their U.S. stores then it adds fuel to the fire that it's not being allowed in Canada.