singer vs songster

singer

noun
  • A person who sings, often professionally. 

  • A machine for singeing cloth. 

  • A person who, or device which, singes. 

  • dance figure with a fixed structure, sung by a caller, or a piece of music with that structure. 

songster

noun
  • A man who sings songs, especially as a profession; a male singer. 

  • One who writes songs. 

  • A male songbird. 

  • A book of songs; songbook. 

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