purpose vs task

purpose

verb
  • To have or set as one's purpose or aim; resolve to accomplish; intend; plan. 

  • To have (an) intention, purpose, or design; to intend; to mean. 

noun
  • meaning for existing or doing something. 

  • Resolution; determination. 

  • Function, role. 

  • The end for which something is done, is made or exists. 

task

verb
  • To assign a task to, or impose a task on. 

  • To charge, as with a fault. 

  • To oppress with severe or excessive burdens; to tax 

noun
  • Any piece of work done. 

  • A difficult or tedious undertaking. 

  • A process or execution of a program. 

  • An objective. 

  • A piece of work done as part of one’s duties. 

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