What sets apart a street, an avenue, a road (rd.), an alley - a way, and whatever forms of communication tracts I missed - that appear as part of street names on city maps in the US?
Boulevards are generally wide roads that extend for quite some distance, and can be isolated at times like a highway.
Avenues are generally the largest kind of road in a city
Streets are like avenues, but usually a bit smaller, and may, depending on the city, be perpendicular to avenues.
Roads are smaller than streets and tend to be found on the outskirts of cities or in the suburbs/country.
Alleys are narrow roads, usually in the city, and not often meant for driving
Ways are small roads, usually in the suburbs or country.
Keep in mind these are just guidelines and not all streets/avenues/etc. adhere to this.
Way and road are the least specialized of the words you presented, and they both mean a path leading from one place to another, esp. for use by vehicles.
Streets and avenues are rather ambiguously used—in some places, avenues run east-west and streets run north-south. In other places, they are simply part of the name of the road in question. Sometimes, avenue is used for wider roads. Sometimes it isn't.
Alleys are easily defined, however; they refer to a narrow passageway behind or between buildings.
Other words, such as boulevard, are just as ambiguously used as avenue and street. Technically, a boulevard is a bit wider than your average street or avenue, though.
It's all a mess, really, and in the end they're all just roads, save for alley, perhaps.
There is no consistency at all in the designation of roads, avenues, streets, lanes, ways, or other paved surfaces in (most of) the U.S.
Even their traditional meanings (lanes are narrow passages, avenues are broad) are no guide. The word at the end "street","way",etc is just part of the name, to be remembered instead of deduced.
I think as time goes by, these increasingly tend to be more alike.
- A street is usually a place (but can be as long or longer than an avenue)
- A road, usually leads to places (but as cities grow, are more like streets)
- An alley usually comes to an end, or its just a narrow road (typically small for cars)
- Avenues are big long streets that usually cut through very large areas (cities or even states
- A boulevard in modern days is more of a big area surrounded by big streets (as a place with trees and flowers)
- A court is usually a very short street leading to a court of houses or something like that