relevant vs thematic

relevant

adj
  • Related, connected, or pertinent to a topic. 

  • Directly related, connected, or pertinent, with important ramifications or implications. 

  • Not out of date; current. 

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 relevant and thematic occurred in a corpus of books? (source: Google Ngram Viewer )