How is this different from the split decision kit?

Actually this kit is the hardware provided/needed for factory split snowboards. If you find a factory splitboard that doesn't have the hardware, this is what you buy. If you want to split your own, or have Mountain and Terrain Technologies do it, then you buy the split decision kit. M n' T Tech does install the setup to be like the factory splits, i.e. rotating system; so you could purchase this if having your board split and you want the rotating system.

The split decision kit is used to convert an old board into a split board, while this is what holds your bindings to your new splitboard.