Mini DisplayPort is a passive technology through which connections can be created from a source to a display. It was released to replace connectors used in older macs. On the other hand, Thunderbolt is a similar technology, but it connects both Mini DisplayPort and PCI Express inside a single cable. With a Thunderbolt port, you can easily connect your drives to your MacBook, and you can also connect external displays to your MacBook.
Since a Thunderbolt combines both Mini DisplayPort and PCI Express connectivity, it can connect Mini DisplayPort peripherals. However, Mini DisplayPort cannot connect to Thunderbolt-enabled devices. While Mini DisplayPort is capable of sending high-definition audio and video from a source to a display, the Thunderbolt gives access to other connections such as networking, peripheral, storage connection. Most times, to use Mini DisplayPort, you need to connect a Mini DisplayPort to a DVI adapter. In terms of performance, Thunderbolt offers faster connections compared to Mini DisplayPort.