The guardian has a wind/waterproof membrane, it has like a brushed quieter face, and it has more down. It won’t pack up nearly as tight as the ptarmigan though. The ptarmigan is like a traditional down puffy and this is more like a big hunting coat that uses down as insulation. This also has a harness pass through and the ptarmigan doesn’t.
I bought It from a guy who said he only wore it a couple times, i haven’t worn it outside of trying it on, I just don’t hunt in cold enough weather. I don’t think you would be able to tell it apart from a new one.