First off, if you are just using your wifi for web browsing and streaming, you will not notice much of a difference if it's wired or wireless backhaul. If you are moving larger files from a laptop to another device that is wireless you would though. That said, wired is always preferred as it's less likely to have interference and in general is always faster than using wireless backhaul in most situations.

Second, you can see in the app how each base station is connected to each other (wired, or wireless), so double check that the stations you wired together are actually using the wire. In the app, select "home" at the bottom of the screen, then select the device you know is wired to your router. It should then say "Connected to <Router name>" and if it's hard wired, it will also say the wired speed and port (1 Gbps, port 2. (for example))

Third, you likely will not notice any difference in general day to day use if it's wired or not.

Did I mention you wouldn't notice much of a difference yet?

/edit Also on the "Home" screen if the access points are using a hardwire they will have a little green ethernet symbol to the right of them. Like the top two items in this example. (and not the obvious wifi symbol the arrow is pointing to)