title_body: How are coffee beans differentiated?
upvoted_answer: It is important to have in mind that altitude is not the only feature that allows one to differentiate the coffee beans. Temperature is perhaps even more important (altitude influences in the temperatures suffered by a coffee plant, but not all the same altitudes mean the same temperature profiles).
  
  As a brief summary (taken from [1]), we can say that:
  
  
  Lower elevations (Robusta species) mean a more intensely coffee flavoured bean (more caffeine).
  Higher elevations (Arabica species) mean more acid and complex taste.
  
  
  So, the main factor is the species of coffee. The elevation and temperature only tell you what of the varieties of these species you can successfully grow and how you can harvest it.
  
  
  
  According to this source [2]: The Effect of Altitude on Coffee Flavor, that relates only to the Arabica species, can be summarized as follows:
  
  
  Altitude contributes to a coffee taste profile.
  Ideal growing conditions for the coffee tree:
  
  
  At the coffee belt (a band extending approximately 30° north and south of equator).
  At high elevations, between 3,000 feet (914.4 meters) and 6,000 feet (1828,8 meters) and beyond.
  These conditions provide a frost-free climate.
  Averaging 60°F (15.56°C) to 70°F (21.11°C) year round.
  
  Cooler mountains provide a slower growth cycle for coffee tree.
  
  
  This means deeper and more interesting flavours (due to a longer maturation process).
  
  Better drainage of soils means less water in the fruit.
  
  
  Further concentration of flavours.
  
  More fertile the soil, the better.
  
  
  A volcanic soil is often preferred.
  
  The farther we are from the coffee belt, the less elevation we must grow coffee tree in order to avoid low temperatures.
  
  
  As a more specific summary:
  
  
  Generally speaking, more elevation implies a more pronounced and distinctive flavour profile:
  
  
  From the simple, mild and subtle of those grown at 2,000 feet (609,6 meters).
  To a fruit, spice, floral profile for those grown at 5,000 feet (1524 meters) or above (when possible).
  
  
  
  
  
  This other source [3]: Bean Basics: Planting &amp; Growing Coffee deals with how altitude affects the planting and harvesting of coffee tree, not about its features.
  
  
  
  [1]: What’s So Important About High-Altitude Coffee? 
  [2]: The Effect of Altitude on Coffee Flavor 
  [3]: Bean Basics: Planting &amp; Growing Coffee