In the midwest anyway when my folks were growing up, there used to be a Tap in many small towns. A Tap is a drinking establishment that sells beer only. Thus the term "on tap".
A Bar or Pub sells beer and wine but no hard liquor.
A Tavern which many small towns have now sells all manner of alcohol but also serves food.
A Lounge or Club sells food and liquor but also features some sort of entertainment.
Anyone else care to weigh in?