a bit vs slightly

a bit

adv

  • To a small extent; in a small amount. 

  • Slightly; rather. 

  • Very. 

  • A lot. 

slightly

adv

  • To a small extent or degree. 

  • Slenderly; delicately. 

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