ear bud vs earphone

ear bud

noun
  • A small earphone designed to be placed in the ear canal for use with portable sound systems. 

  • An immature ear of maize from which the threadlike silks emerge. 

  • An underdeveloped mammalian ear. 

  • A cotton swab. 

earphone

noun
  • A transducer that converts electric signals into sound and is held near the ear, especially as part of a telephone; an earpiece or headphone. 

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