We were on subject and tuned pipes work on the same principle on glow or ignition two stroke engines of any displacement. The OP got the answer he was looking for,
AFAIK all he wanted to know was the terminology difference for clarification, and not a technical dissertation on the operation of various forms of tuned pipes. Then those who answered previously chatted for a few posts about a common related interest and posted some examples of tuned pipes in other applications. I don't see the problem..
As for the OP - tuned mufflers are compact, convenient, and easy to fit, and they provide some boost but are generally not capable of providing the same level of boost as a full tuned pipe. Jett for example, has the standard Jettstream tuned muffler system for it's .40/.46/.50/.60 engines, but also offers the SS muffler or the race muffler, each tuned for higher rpm ranges and more specialized use. The use of tuned mufflers in pylon racing was a subject of debate some years ago as the people who started using them basically called them mufflers, while those who didn't think they should be used called them warmed-over tuned pipes contrary to the rules. They are in wide use so I guess the muffler crowd won. They are an excellent choice for someone who wants to try an aftermarket system on their sport engines for a little more power, without the learning curve and logistics of a tuned pipe installation. For example, there are Jettstream and Nelson Ultrathrust tuned mufflers for the very common OS .46 FX, and you can pick up a fair amount of top end power and still have a lot of your midrange freedom just by bolting one on and using an appropriate prop for the effective rpm range of course.
MJD