According to independent European tests (EN 13537), the Orion is a 30F bag and the Pounder Plus is a 36F bag. Both use Primaloft Sport, a decent synthetic fill. It is more compressible and drapes better than continuous filament fills like Polarguard. I actually have an Orion and it keeps me warm down to 30F, not 20F, as TNF claims. It has a 60" shoulder girth compared with the 62" girth of the Pounder Plus. I like the Orion a lot but use it mostly as a loaner now that I have something better, the Montbell UL Alpine Burrow Bag #3.