Merging Spectrum WiFI 2G and 5G with Airport Utility?

I just upgraded my home wifi to Spectrum, and my current wifi always has a 2G and a 5G connection

Does this mean that the Spectrum WiFi is producing a 2.4 GHz and 5 GHz network using the exact same wireless name......or.....does this mean that you see two different networks......a 2.4 GHz and a 5 GHz network.....when you click on the WiFi menu at the top of your Mac's screen?

"Join a wireless network" is the correct setting for the AirPort Express if it connects to the Spectrum WiFi using a wireless connection.

The "create a wireless network" setting would only be used only if the Express connects back to the Spectrum WiFi router using a permanent, wired Ethernet cable connection.

If the Express connects using wireless, it can only "Join a wireless network" using either the 2.4 GHz signal....or....the 5 GHz signal.....but not both simultaneously.

Unless the AirPort Express is located very close to the Spectrum WiFi router.....in the same room or very close proximity to the Spectrum router......you should have the Express connect to the Spectrum 2.4 GHz network......since those signals are stronger than the 5 GHz signals.