Sonos Radio Query

[interstellar]

I have a sonos set up round the house and use Spotify. I really like listening to the spotify powered sonos radio.

Sometime I listen to it based off an artist through the spotify app and mostly I use the artist radio through the sonos app. The playlists are different to one and other even tough its the same artist??

I thought Sonos was just using an interface into Spotify so why different songs?

I really want to save the radio from the Sonos version as the playlist goes on and on but I cant see this. Is it even possible to save a Sonos radio playlist?

I cant find anything online so thought I would check here.

Thanks in advance.