This is a Traffic Circle, not a Modern Roundabout. Here is an example of a traffic circle at the intersection of Golf Rd. and Wolf Rd. in Des Plaines, Illinois.
This Traffic Circle requires drivers to stop before entering the circle. A modern roundabout only requires drivers to yield, therefore, traffic is constantly moving.
Unlike a modern roundabout, this traffic circle does not have uniform entrances and exits, thus limiting traffic flow.
Too many legs. Modern roundabouts are not designed to have more than four legs to an intersection.
This example is a full-stop roundabout in Hawthorn Woods. The distinct feature that makes it different than a modern roundabout is that on each leg there are stop signs. You can see the white stop bar on each entrance into the circle. This is similar to a modern roundabout, but does not provide the traffic flow efficiency of a modern roundabout. This is basically a four-way stop intersection with a landscape median. Communities usually implement this style of intersection as a method of traffic calming.
All of the following characteristics make this a modern roundabout:
Traffic yields to other cars in the roundabout.
Splitter islands on each leg of the intersection to aid traffic flow.
A truck apron to accommodate larger vehicles.
Pedestrian crossings set back away from traffic in the roundabout.