mottle vs reskin

mottle

verb
  • To mark with blotches of different color, or shades of color, as if stained; to spot; to maculate. 

noun
  • A distinguishing blotch of color. 

  • A mottled coloration or pattern. 

reskin

verb
  • To change the skin, or visual appearance, of an application. 

  • To replace the skin of a motor vehicle, especially so as to market the same car under different brands 

noun
  • Something that uses the exact same model as something else, but has superficial differences such as textures. 

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