singer-songwriter vs topliner

singer-songwriter

noun
  • A musician who both sings and composes, especially when recording or performing his/her own compositions. 

topliner

noun
  • One who contributes to contemporary songwriting by creating vocal melodies, lyrics, or hooks related to the vocal in a song. 

  • One who is billed as the primary entertainer. 

How often have the words singer-songwriter and topliner occurred in a corpus of books? (source: Google Ngram Viewer )