Interesting, I can't find listings for exhaust soot traps...People call them that sometimes incorrectly. So do some suppliers.
A cat actually has rare metals that when heated are a catalyst for altering certain chemicals in a he emissions gasses.
A soot trap is just that- think airfilter except that this collects and stores a grade of carbon and doesn’t let all of it pass through instead of dust.
A cat is very expensive and a soot trap is slightly more than a muffler.
Thanks FERM, I have a better handle on the tech now, I see for diesel ceramic core types and the precious metals versions along with the big price swing Will L. mentions.You have to keep in mind with diesels there is the old style diesel cats that weren't much more than soot traps that held the big soot particles until they broke down, and now they have reactive catylists that have precious metals in them that work in conjunction with the DPF and urea injection systems.