From what Google searches I’ve read it seems that one big difference that’s obvious is that Canada has cut defense spending first in lieu of any changes to domestic programs the past couple decades. Canadian defense spending is currently 1% of GDP and for the US it’s 3.5% of GDP.
And now that Canada has been told to carry their own water in terms of aggressive Russian border incursions that will have to change. I was pretty shocked that Huff Post - Canada just destroyed the sad dilapidated state of the Canadian defense forces.
There difference in federal spending is about 8%, defense spending only explains 2.5% according to your figures.
Also, US could easily spend 2.5% instead of 3.5% on defense without losing its status. The defense lobby will never let that happen though. Don't confuse corporate profit seeking with national security.
