Ethernet versus Thunderbolt2

My main computer is a retina iMac which has a Thunderbolt Display attached to it directly. When just using my main computer I use both monitors on it.

I use Jump Desktop in a separate space so I can 3-finger swipe to an attached M1 Mac mini - I tend to do this on the thunderbolt display. For this I normally have an ethernet cable directly between them to maximise image quality.

Today I was testing things and tried using a Thunderbolt 3 to Thunderbolt 2 connection from the M1 Mac mini to the Thunderbolt Display instead of Ethernet. It worked fine. which leads me to wonder which is best? and could I, if I got 3rd Mac could I have one using Ethernet and one using Thunderbolt... so two Macs networked separately to a single iMac. I assume I could?