They are not almost the same shape. They are the same shape. Thanks for trying to help.
I didn't say TBolt and DP were almost, I said USB and DP were almost. Sarcasm; I've been doing it longer. Need to be pedantic, too.
Yes, Thunderbolt is a combination of Displayport signals and PCIe signals, muxed onto a single physical connection. TBolt ports can talk to DP devices, the reverse is not true.
I'm fairly certain that you *could* get a mini-DP port to give a signal to a TBolt monitor, but Apple's TBolt monitors are actually more like combination monitors and I/O hubs. Because of the way Apple laid it out and locked it down, it requires a TBolt port to talk to, as you noted.
But to go back to your initial question; "Radeon card with mini-DP outputs + TBolt monitor"? No go.