To clarify: USB C is the port itself (the mechanics).
On top of that go the different supported features/protocols. Both ports support USB 3.1 (data), USB PD (power), DisplayPort (display), but only the upper port supports TB3 (external PCIE).
Docks and Hubs don't necessarily need TB3. I plan for a USB-C dock (with DP) at work and a TB3 eGPU dock at home.