"Sociolect" distinguished from "dialect"

From this month's Atlantic:

...sociolect: a language variety that’s spoken within a social group, like Valley Girl–influenced ValTalk or African American Vernacular English. (The word dialect, by contrast, commonly refers to a variety spoken by a geographic group—think Appalachian or Lumbee.) Over the past 20 years, online sociolects have been springing up around the world, from Jejenese in the Philippines to Ali G Language, a British lingo inspired by the Sacha Baron Cohen character.