retro vs retrospective

retro

adj
  • Affecting things past; retroactive, ex post facto. 

  • Of, or relating to, the past, past times, or the way things were. 

noun
  • Past fashions or trends. 

retrospective

adj
  • Affecting or influencing past things; retroactive. 

  • Of, relating to, or contemplating the past. 

  • Looking backwards. 

noun
  • An exhibition of works from an extended period of an artist's activity. 

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