Use iMac as a monitor for MacBook
I have a 21.5-inch, Late 2012 iMac running macOS Mojave and a 2016 Macbook Pro running Catalina. I am trying to use the iMac as an external monitor for my Macbook and I've found that I need a Thunderbolt 3 to Thunderbolt 2 adapter as well as a Thunderbolt cable.
How does the Thunderbolt 3/Thunderbolt 2 adapter differ from a USB-C/Mini DisplayPort adapter?
Also, I've found that Target Display mode does not work on macOS Mojave. Does this mean that I will not be able to use the iMac as an external monitor for my Macbook regardless of the adapters and cables I have?
[Re-Titled by Moderator]