While mini display port and thunderbolt 2 share the same form factor, there are several key differences

1. Thunderbolt 2 has a 20 Gbps bi-directional channel instead of 10 Gbps
2. Thunderbolt 2 supports 4K video (a video format that has four times the resolution as 1080p
3. Each Thunderbolt 2 port also provides up to 10 Watts of power to connected peripherals.