Can a USB-C to mini DisplayPort cable be used with USB-C to Thunderbolt ports?

I have the above cable for my current set up of sending display from my PC laptop with a USB-C port to my 2010 iMac with a mini DisplayPort port. It works great.

I have now bought a mid-2011 iMac that does not have a mDP port. It has a Thunderbolt port. Which I guess is Thunderbolt 2.

The current cable is not working with this new set up (even though it will plug into the Thunderbolt port) and I cannot work out if the problem is trying to use the cable itself or if I am not setting it up properly.

So do I need a different cable if the only thing that is changing in the configuration is that instead of a mini DisplayPort on the iMac, I have Thunderbolt port on the iMac.

From other answers I think I might need a different cable but I still can’t quite work out what, or if I need one of those very expensive apple adapters.

Here are some basic rules about Thunderbolt and DisplayPort cables:

• Any Type C Thunderbolt 3 cable is also a USB-C cable. Only quality USB-C cables are also Thunderbolt 3 cables. In other words, avoid cheap ones.

• Thunderbolt 1 and Thunderbolt 2 cables, while they carry the mDP signal are not mini DisplayPort cables. mDP cables are not Thunderbolt cables and vice versa.

• Thunderbolt cables can only be used on Thunderbolt ports.

• mDP cables can be used in either mDP ports or Thunderbolt ports

_{Source: TrippLite.com}

So do I need a different cable if the only thing that is changing in the configuration is that instead of a mini DisplayPort on the iMac, I have Thunderbolt port on the iMac.

Yes. The 2011 iMac (27" only) support Target Display Mode via Thunderbolt only. You will need the following:

• Thunderbolt 1/2 cable
• Thunderbolt 3 to Legacy Thunderbolt Adapter

The 2011 iMac is a very different animal compared to the 2010 that uses DisplayPort. To connect to it via Target Disk Mode, it requires a TB connection. So you'll need a proper adapter and cable to make this work.