For the listed SSD.
One has no bracket and cable while the other does. If your case has a spot for 2.5inch(or you can drill some holes
) drives and you have a spare SATA cable you do not need to pay extra for it.
You can also get another M4 with a notebook kit that includes a USB -> SATA adapter for cloning your old drive to the new one.
Some times you will also get OEM drives with no cables and they just come in an anti static bag vs a retail(cost more) drive with a nice box and cable ect.