Distinction Between The Two Terms

• The two terms are synonymous: their distinction comes from their origins.
  
  

Bush

• Bush comes to English from the ancient German word "busk," and was rendered in Old English as "bysc."
  
  

Shrub

• The word 'shrub' comes from Scandinavia. It is uncertain which language produced the word first, but related words include the Danish word "skrub," the Norwegian word "skrubba," and the Flemish word "schrobbe."