ok so the 3d is a midi fighter classic with 3d function and the bank buttons on top.The spectra has no 3d function, no bank buttons on top, but you can design it really cool like. Each unit includes 6 shift keys. These shift keys are for extra functions you assign in the utility or DAW/DVS. In the spectra you can assign 2 shift buttons to switch from last back to next bank, 2 on the other side for switching mappings and the last 2 you can use them for play buttons leaving your 16 arcade buttons doing more important features like launching loops in the remix decks or instant gratification or even the loop recorder. So basically the 3d has the 3d function, 6 shift buttons and bank buttons on the top of the unit. THe spectra only has the 6 shift buttons which you can assign to do anything. ps. the shift buttons the 3d has also can do extra stuff, just incase you were asking.