My understanding is that the term 'Canadian' for description of a pipe came first. The early French explorers adopted the native american design of the smoking pipe (the calumet) with its flattened shank/stem carved and drilled from a single piece of wood, with the bowl carved from pipestone from what would become southern Minnesota. The French explorers, being traveling men, naturally reduced the length of the shank/stem to be more handy. When pipes began to be made from briar, the shape was retained, as it was a favorite of many French-Canadians at the time; some of which had emigrated to the USA.
The term 'Lumberman' was coined by Swedish emigres working in the lumbering business in the northern tier of the USA, from Michigan west to Washington and Oregon. They liked the style of the 'Canadian', but due to ill feelings over boundary disputes on timber tracts, wanted to call the pipe design by a name other than 'Canadian'.
Accurate account? Who knows? But it was told to me by my great-grandfather, who was a steam locomotive engineer who worked in the Washington state logging area in the late 1800's.