exterior vs tip of the iceberg

exterior

noun
  • Foreign lands. 

  • The outside part, parts or surface of something. 

adj
  • Being from outside a country; foreign. 

  • Outdoor. 

  • Relating to the outside parts or surface of something. 

tip of the iceberg

noun
  • A small indication of a larger possibility; the first part encountered of a problem that is much bigger than it seems. 

How often have the words exterior and tip of the iceberg occurred in a corpus of books? (source: Google Ngram Viewer )