Primarily the term resting bag basically implies a protective bag for somebody to sleep in. A wet down sleeping bag is very hard to dry out as well as is considered even worse than having no resting bag at all. One more kind of resting bag is the mommy bag. Unless you are intending a trip to an extremely chilly climate and also resting outdoors after that you will most likely be better with rectangle-shaped sleeping bags over a mommy style bag. These bags have a particular usage and they are really certain, extremely cold climate, mommy sleeping bag.
The other sacrifice is the size or thickness of the bag. A mummy sleeping bag essentially will certainly be much smaller sized for bring around which is why it is a preference for many backpackers/hikers. The rectangular resting bag isn't as small yet because it's not common to be lugging it, apart from somewhere in a vehicle while getting to your intended location, the bulkiness of the bag is not as large a problem.
The last greatest factor to consider in selecting a bag is the insulation that is used in that bag. While both will do the work to maintain you warm, they both have their pros as well as cons. Some kind of extra padding under the bag is very advised.