There’s several variations true. TB1/2 used the same connector as the miniDisplayPort standard for backwards compatibility with miniDP. Since Thunderbolt is not only a data port standard but is fully VESA compliant with the DP/miniDP/usb-c, the new TB3 standard shifted to the newest DisplayPort standard using usb-c for data and display.
But because it’s a standard for both data and display connections, you can almost always find a combination of adapters and/or varied-end cables to hook up what you need between legacy devices and current be it DP/miniDP/usb-c or TB2/TB3/usb-c/FW.
Intel (who owns the trademark “thunderbolt”, not Apple) and Apple, when they collaborated to design the thunderbolt interface, were explicitly trying to develop one port and one combined standard for any and all data - combining the USB consortium data standards and the DP consortium display/audio standards.
The TB3 standard connector as usb-c is just the evolution of Intel developing one small connector type that handles everything, but it does mean chasing adapters to keep older hardware connected.