1. Thunderbolt 2 :
Thunderbolt 2 is released in 2013 that is the second iteration of Thunderbolt standard. Like the Thunderbolt, it is based on the Mini DisplayPort connector that is developed by Apple that means it is compatible with any USB port And its cable also will not fit in the Thunderbolt 3 port. Thunderbolt 2 offers a maximum throughput of 20 Gbps which is twice the throughput of Thunderbolt and half the throughput of Thunderbolt 3.
2. Thunderbolt 3 :
Thunderbolt 3 is released in 2015. It is the newest and fastest version of Thunderbolt that can offer a maximum throughput of 40 Gbps. Unlike Thunderbolt 2, in Thunderbolt 3 USB
Type-C connector is used and it is backward compatible with USB 3.1. Also it offers 100 W power to that devices.
We can distinguish Thunderbolt 2 and Thunderbolt 3 port. if port shape is like mini DisplayPort then definitely its either Thunderbolt 1 or 2. And if the port shape like USB C it's a Thunderbolt 3 Port.
Difference between Thunderbolt 2 and Thunderbolt 3 :
