"Well drinks" and "call drinks" are categories that cover most of the drinks you can order at a bar, and if you want a more specific drink made to your liking, order a call drink.
Well drinks, like a rum and Coke, are often made with the cheapest and most generic alcohol available in a bartender's "well," or their immediate work station.
Meanwhile, call drinks, like a Bacardi and Coke, are more specific, and involve the drinker asking for their preferred brand of the liquor(s) used in the cocktail.
The request of a certain liquor brand or product differentiates call drinks from the well drinks, which are more of an umbrella category that can use any brand of ingredients.
Learning which liquor brands you like can help you order a call drink you know you’ll enjoy, but if you want to keep your budget in check, a well drink may be better.