regional vs thematic

regional

adj
  • Of, or pertaining to, a specific region or district. 

  • Of, or pertaining to, one part of the body. 

  • Of a state or other geographic area, those parts which are not metropolitan, but are somewhat densely populated and usually contain a number of significant towns. 

  • Of, or pertaining to, a large geographic region. 

noun
  • An entity or event with scope limited to a single region. 

thematic

adj
  • Relating to, or having a theme (“subject”) or a topic. 

  • Relating to a melodic subject. 

  • Of or relating to a theme (“subdivision of the Byzantine empire”). 

  • Of a word stem, ending in a vowel that appears in or otherwise influences the noun or verb's inflection. 

noun
  • A postage stamp that is part of a thematic collection. 

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