building society vs savings bank

building society

noun
  • A type of financial institution which traditionally was based on lending money (as mortgages) to society members to buy houses, from other members pooled savings and/or money borrowed wholesale. 

savings bank

noun
  • A type of financial institution that focuses on retail banking: savings of private depositors, payments, credits and insurances for individuals or small and medium-sized enterprises. 

How often have the words building society and savings bank occurred in a corpus of books? (source: Google Ngram Viewer )