Let me understand the Thunderbolt/USB 4 ports of the new iMac

The top model of the new iMac to be launched by the end of May 2021, is said to come with 2 Thunderbolt/USB 4 ports and 2 USB 3 ports.

In my mind, Thunderbolt is a physically different connector compared to the other 2 USB 3 ports, but looking at this picture they are apparently the same port.

I have an old 2012 iMac connected to two external TVs through the thunderbolt port. Each port using a thunderbolt to HDMI dongle. I am not mirroring the main screen. I have 3 independent monitors, the iMac one and each TV.

So I thought, I could do the same to this new iMac. I disconnect the dongles I have on the old iMac and connect to this new one but apparently these “thunderbolt” ports of the new iMac are in fact USB-C ports that deliver thunderbolt. So, In fact I need USB-C to HDMI dongles, right?

So, physically speaking, this new iMac only has 4 USB-C ports, two of them being able to deliver “thunderbolt”, right?

This new iMac has two of these “thunderbolt” ports but apparently if I use both, I will not get two external independent monitors right?

Why?