What is the difference between them? I want to quiet things down, but I don't want to restrict flow.

 

Pending your point of view, they're all mufflers.

The short story is that the baffled type of muffler is good for attenuating the low frequency sounds. The baffles themselves can contribute to some high frequency noise though . . . . . it's weird science there.
The resonator (often called glass-packs), is good for attenuating high frequency sounds. They pass the low frequency noise.


The two combined are what you'd expect to find on the really quiet cars and trucks.

Good reading . . . . . http://auto.howstuffworks.com/muffler.htm

Check out the BHM (Big Honkin Muffler) thread linked to in my Sig.

Otherwise, everybody and their brother makes mufflers. With that they all say theirs is the best. Best at what?

If you're wanting to make your exhaust system quiet, yet breath freely, do some homework. You'll find not all are created equal.

Dig through the info Donaldson offers regarding their product and you'll find many that are the same on the outside, yet perform VERY differently in terms of noise attenuation, frequency attenuated, back pressure, etc.

Dig around in here ~ https://dynamic.donaldson.com/webc/W..._Company_Store