ahead of vs instead of

ahead of

prep
  • Preceding. 

  • In front of. 

  • Having made more progress than. 

  • In the future of. 

  • In advance of. 

instead of

prep
  • In lieu of; in place of; rather than. 

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