Really? One is about 80% longer than the other
All of the 'muffling' on a straight-through muffler comes from the gas' compression waves expanding within the muffler housing. The holes allow that expansion, and the fibre-glass inside absorbs it like a sponge.
Even the profile of the muffler has an effect, with oval ones being more effective because they flex more. Even the size of the holes in the internal tube have a large impact on the effectiveness.
A short muffler needs to be carefully designed to avoid being ineffective, and that's where we sometimes see aesthetics being chosen over practicality. Remus pipes are similar, where they are mid-length but have gone for a slender look, which means less absorption, so I personally find them loud and tinny if you use them with a decat, although they sound fine with the cat fitted, which is how they were designed to work.
Making mufflers is like making a musical instrument. Something that looks awesome might sound terrible, and getting someone to design a solution for your needs means either finding a manufacturer who makes a muffler specifically for your setup, or finding someone who will make one specifically to suit your setup. My Meerkat was designed specifically to go with the cross-pipe, and during the discussions Peter warned me it would be louder if it was that short, but that he would design it as best he could to not be too loud. That's exactly how they came out, with a non-harsh note that is louder than stock but not at all tinny.