One is mounted on a card that you plug into the motherboard (http://www.plextoramericas.com/index.php/pcie-ssd/hhhl/pcie-m6e) and one is plugged into an m.2 port on the motherboard (http://www.plextoramericas.com/index.php/pcie-ssd/m2/m6e-m2-2280).
One is mounted on a card that you plug into the motherboard (http://www.plextoramericas.com/index.php/pcie-ssd/hhhl/pcie-m6e) and one is plugged into an m.2 port on the motherboard (http://www.plextoramericas.com/index.php/pcie-ssd/m2/m6e-m2-2280).
I'm not sure. It looks like the same drive with the only difference is that one is mounted on a card. Whether or not the PCI-E slot will make a difference in performance I don't know.