fit wise, the Canada shirt is a closer fit, more like a regular shirt, but with space underneath for some decent thermals. the Swannie is a much looser fit, i guess because it is a pull on. the Canada's wool is softer and i reckon slightly thicker but the swannie is probably more hard wearing, but i find it is a much coarser material that can feel a bit scratchy. the Canada i feel is definitely warmer, but i only wear it in winter, the swannie is great for autumn, spring as well.
if i had to choose between the 2.....
i think i'd go for the Canada, as it is more of an everyday wear. both have pros and not many cons. but i prefer the fit and the softer wool of the Canada.
i hope this helps mate.