People mess this one up all the time. You'll seem them do a 30-50 mile ride and call it recovery because they weren't hammering it. But they will still have a TSS score from 65-120 from the volume.
Recovery rides are small, little, their only purpose is to get the blood flowing to the areas that need to recover for 20-45 minutes. A TSS of 20 or less.
I chose to ride to a coffee shop 2 miles away, slowly, drink coffee. Then I go home.
Don't over think it, and don't mistake endurance rides for recovery. :)