anyway vs that is

anyway

adv
  • Used to indicate a change of subject. 

  • Used at the end of a question for emphasis, or to direct the conversation to something of more broad importance (compare with more to the point). 

  • Regardless; anyhow. 

  • Used to indicate that a statement explains or supports a previous statement. See anyhow and at least. 

that is

adv
  • In other words; that is to say. Used to introduce a clarification or explanation 

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