«Further, according to the contemporary view, the term "URL" does not refer to a formal partition of URI space; rather, URL is a useful but informal concept. A URL is a type of URI that identifies a resource via a representation of its primary access mechanism (e.g., its network "location"), rather than by some other attributes it may have. Thus, as we noted, "http:" is a URI scheme. An http URI is a URL. The phrase "URL scheme" is now used infrequently, usually to refer to some subclass of URI schemes which exclude URNs.»
How much glue will I have to huff before that RFC makes sense to me?