I am looking for a new bag for winter camping, have been looking at these 2:

https://www.rei.com/product/164851/mountain-hardwear-bishop-pass-0-sleeping-bag-mens

https://www.rei.com/product/147279/big-agnes-anvil-horn-0-sleeping-bag-mens

I am leaning towards the first one, Mountain Hardwear. My only question is it specifies a compressed volume of 10.8L while the Big Agnes specifies 3.94. Since both bags are 0 degree, use the same fill, and are roughly the same weight, how do you explain the vast difference in compressed volume.

Also how does compressed volume relate to stuff sack size? The Big Agnes has a stuff sack that is 5x larger than the compressed size, which I guess means the stuff sack does not compress the bag as much as it could. However the Mountain Hardwear bag has a stuff sack that is smaller than the compressed volume, which to me would mean the bag could not fit in it's own stuff sack.

Is compressed volume a mostly meaningless number?

Thanks for the input guys.