I happen to live on a "Circle," which, as is often the case, is not a circle at all. It's actually a semicircle, a half-moon if you will (imagine a spur off the main road that's shaped like a half-moon). A "Court" in my neck of the woods is, in effect, a circle, since it usually approximates a full moon (or, better, a lollipop...there's usually a straight-away off the main road which leads to the circle, and the whole thing is called a "Court"). "Streets" and "Roads" are generally "secondary" thoroughfares, which means that they (ostensibly) carry less traffic. "Avenues" and "Boulevards" by and large are "primary" thoroughfares with traffic aplenty and multiple lanes in either direction. Of course, there are "Streets" and "Roads" that boast scads of traffic and lanes galore (see, e.g., "Main Street" or "Boston Post Road") and "Avenues" and "Boulevards" that consist of only two lanes and carry little traffic on a daily basis, but these appear to be exceptions to the rule.
As for additional thoroughfare denominations, in my neck of the woods we have "Ridge", as in "Long Ridge," "Hill," as in, "Strawberry Hill" or "Chapel Hill," and "Park," as in "Union Park." For whatever reason, my burg's founding fathers and mothers saw fit not to add "Road," "Street," "Drive," etc. to these denominations, as is the standard practice. This has created, somewhat confusingly, a situation where you can have both "Long Ridge" and "Long Ridge Road," or "Strawberry Hill" and "Strawberry Hill Drive." I suspect that mail carriers and flower deliverers, among others, are none too appreciative of this disjointed system of thoroughfare-naming.
John
