as it is vs that is

as it is

adv
  • Used other than figuratively or idiomatically: see as, it, is. 

  • In the actual circumstances (and often contrary to expectations). 

  • Already; without adding further difficulty or complexity. 

that is

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

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