This is really true, they do have a dedicated disc with blades and a vacuum function just for the mulching process, if that works as advertised there is matter to brag about.

The "unique mulching system" is just marketing hype to try to make them look fancy. It's what every other mower does. Makes me really question any of the other claims they make when such a basic feature is hyped like that.

The blade and deck design pulls a vacuum on the grass (there are a lot of different variations of doing this depending on your blade design, and good decks really help with this) then blade design either cuts or cuts and rechops the grass blades, and either bags or redeposits the grass.