Howdy,
Windsor is now owned by Blount, who also owns Oregon. Windsor's plant is in Tenn. Oregon's is in Canada.
The bars are roughly equivalent, though some differences exist, and some logger's will believe in only Oregon, or only Windsor. For years Windsor was the best, but now I would claim Oregon's top of the line bars as equivalent, or perhaps even slightly better.
The best bars have the teeth on the sprocket wheel thinned as they come out to the tips. The groove must be tight enough that the next gauge chain will not go in at all. Ideally, this means called gauge plus .001 to plus .003. Groove width is the life determining factor number one in a long bar.
Regards,
Walt Galer