Are hdmi 2.0 and 2.1 connections similar?

I want to buy the xbox series x next year and my main question is whether an hdmi 2.1 cable will fit an hdmi 2 connection. That always leads to confusion for me and i'm not really technically informed.

Yes. As far as I know, the HDMI connection is mechanically identical.

But the functions supported are completely different. You can also operate an HDMI 2.1 device (these are only the new consoles anyway) on a normal HDMI 2.0 TV, but then you can't use 4K @ 120Hz and probably not VRR either.

In short: the devices work together, but the one with the lowest HDMI standard determines the range of functions.

It is identical, but the bandwidth and the hz number are different.

Yes, it works, but it doesn't have all the functions as with the HDMI 2.1 connection (e.g. The 4k 120hz). But if you already have an HDMI 2 device, in my opinion the upgrade to HDMI 2.1 is not worthwhile