What's the difference between a down sweater...
What's the difference between a down sweater & a down jacket?
Patagonia calls these sweaters because they are often used as a part of a layering system, but they do have a DWR coating so they are fine to use as a "jacket" as well. These (as well as similar offerings from TNF, Mountain Hardwear, Mont Bell, etc) will usually compress down really small. Many of the down pieces labeled "jacket" in the Patagonia line are less compressible, use heavier fabrics and are more geared towards being the outermost layer in your kit.
The general distinction in marketing between a "sweater" and "jacket" when you're looking at down pieces is the amount of fill. "800" refers to the quality of down inside (1 ounce lofts up to a volume of 800 cubic inches, roughly), but what really determines the warmth is how much down is the jacket stuffed with. Less than three ounces is generally a sweater, and greater than three is a jacket. To a lesser degree, items defined as jackets are sometimes designed specifically as outer layers, with more durable, or waterproof fabrics, instead of flyweight ripstop shells.