If Thunderbolt 1 & 2 is Mini DisplayPort, Mini DisplayPort must also be Thunderbolt? Right? Wrong! There is a lot of confusion around Thunderbolt, Mini DisplayPort and connectivity. This is because both Thunderbolt and Mini DisplayPort use an identical connector, and the only difference is that the Thunderbolt connector can carry (in addition to the Mini DisplayPort), a Thunderbolt signal, which is a PCI-Express. Thunderbolt is fully compatible with Mini DisplayPort peripherals, and the new port is backward compatible, therefore it can still be used to connect to DisplayPort devices, BUT, only the new port can be used to connect to Thunderbolt devices.
What works, what doesn’t?
The image below shows which combinations of Thunderbolt (TB Cable) and Mini DisplayPort (DP Cable) will (green) and will not (red) work together.
*This diagram refers to Thunderbolt 1 & 2 only
Clearly, there are some cases where the two technologies will work well together, but there are nearly two times as many combinations that will not. Computers with a Thunderbolt connector (usually designated with the Thunderbolt Logo – a lightning bolt shaped arrow), will function when connected to either Thunderbolt or Mini DisplayPort display, provided you are using a cable matching the technology of the display. However, a Mini DisplayPort enabled device will not function when connected to a Thunderbolt display or docking station.
The case for Thunderbolt: more connections
While Mini DisplayPort only allows for connections from your computer to a display, Thunderbolt goes well beyond that, allowing you to connect other Thunderbolt enabled devices such as docking stations, hard drive enclosures and RAID enclosures. When it comes to transferring data from a computer to an external hard drive or RAID enclosure, Thunderbolt offers far greater performance than USB 2.0 & 3.0, and even FireWire 400 & 800 and ExpressCard/PCIe. This is because Thunderbolt operates with two dedicated channels (one upstream and one downstream) each capable of speeds of 10 Gb/s or 20 Gb/s with Thunderbolt 2.
The comparison chart below illustrates just how efficient Thunderbolt is with handling media files :
Also, remember that Thunderbolt cables are required to connect two Thunderbolt devices together.
*This articles applies to Thunderbolt 1 & 2 technology only, Thunderbolt 3.