M.2, sata express and pci-e x4 ssd slot
when connecting one of the newer ssd's are these ports the same? a 4x pcie ssd card, or connecting a ssd to either sata express or m.2
No, that was not my point. The point was that on these connectors the speed is normally limited by the speed of the controller on the ssd. All of these can in principle obtain speeds of 10 GBit/s (~1.1 GB/s), but in reality, the most I have seen on PCIE is ~750 Mb/s. I do not know of any sata express divice on the market, and M.2 pcie has the identical same channels as pure pcie . So this depends on the specific device you want to use.
Are you thinking of this one: http://www.plextoramericas.com/index.php/pcie-ssd/m2/m6e-m2-2280?start=1 and this one: http://www.plextoramericas.com/index.php/pcie-ssd/hhhl/pcie-m6e?start=1 ? These are identical, except that the M.2 pcie drive uses less space. The speeds will be identical, except for manufacturing differences between units (meaning if you get two, you are not guaranteed that both perform the same). So yes, in this case they have identical performance.