Sum or Difference Sudoku (Daily Sudoku League #140)

Sum or Difference Sudoku appeared in World Sudoku Championship 2015 and I prepared this Sudoku for the practice of the India Sudoku Team. I am posting for Daily Sudoku League on Thursday. However, to post many Sudoku puzzles which I prepared for WSC 2015 practice, I will be posting around 3 times a week for about a month before coming back to my previous schedule of posting on Thursday.

Coming to today's Sudoku which is Sum or Difference Sudoku, I have prepared two Sudoku puzzles of this type. Today's puzzle contains some big hints in the puzzle immediately giving the idea that it represents the sum of numbers. However, my other Sudoku puzzle contains only smaller hints in such a way that one has to find it out during solving whether a given hint represents the sum or difference of the numbers. Soon I will be posting my second puzzle. Hope you will enjoy this puzzle and it is always great to receive periodic feedback about my puzzles. So please do spare some time to give your feedback in the comment section of any post.

I am posting this Sum or Difference Sudoku as my 140th Sudoku in The League of Extraordinary Ladies & Gentlemen. Can you solve this Sudoku puzzle variation?

Rules of Sum or Difference Sudoku

Classic Sudoku Rules apply. Additionally, the clue outside the grid indicates either the sum or difference of the two nearest digits in the corresponding row or column.