full-grown vs grown-up

full-grown

adj

  • Fully developed; adult 

grown-up

adj

  • Adult, physically mature. 

  • Of, pertaining to, or suitable for adults. 

  • Having a mature outlook. 

noun

  • An adult. 

How often have the words full-grown and grown-up occurred in a corpus of books? (source: Google Ngram Viewer )