Aha. Traffic circles have stop lights controlling entering traffic. Roundabouts do not.**
I have heard multiple times that both save petrol and are safer; however, I was sure annoyed to discover the fancy ones in the neighborhood above are too narrow for delivery trucks and other long vehicles to negotiate without bumping over the curb and crushing the herbage.
* Word invented for this headline….
** Clarification from Time mag, discussing the trend toward adding roundabouts to our roadways.