field hospital vs nursing home

field hospital

noun
  • A large mobile medical unit that temporarily takes care of casualties before they can be safely transported to more permanent hospital facilities. 

nursing home

noun
  • A place of residence for people who require constant nursing care and have significant deficiencies with activities of daily living, such as the elderly and younger adults with physical disabilities. 

How often have the words field hospital and nursing home occurred in a corpus of books? (source: Google Ngram Viewer )