Book: The Five-Minute Linguist
Chapter: 3. What's the Difference between Dialects and Languages?
While there is no generally agreed-upon way to distinguish between a ‘language’ and a ‘dialect', language can mean the generally accepted standard (the variety sanctioned by the government and/or the media), while dialects are versions of the standard that vary from region to region. Language varieties tend to be labeled dialects rather than languages for non-linguistic reasons, usually political or ideological.