The Basics
Sudoku and Kakuro are both number-placement puzzles played on grids, but the rules are different. Sudoku uses a 9x9 grid and the rule is simple: no repeating digits in any row, column, or 3x3 box. Kakuro uses an irregular grid and requires you to fill in digits that add up to specific sums.
Sudoku: Logic Only
Sudoku does not involve any math. You never add, subtract, or multiply. You just place the digits 1 through 9 so they do not repeat. The challenge is figuring out which digit goes where using elimination and pattern recognition.
Kakuro: Logic Plus Arithmetic
Kakuro is often called a cross between Sudoku and a crossword. The grid has clue cells that show target sums. You fill in blank cells with digits 1 through 9 so that each group adds up to the target, with no repeats within a group. You need to know your addition facts.
Grid Layout
Sudoku always uses a symmetrical 9x9 grid divided into nine 3x3 boxes. Kakuro grids vary in size and shape. They can be small (6x6) or large (16x16) and have irregular patterns of black and white cells, similar to a crossword layout.
Difficulty Comparison
Easy Sudoku is easier than easy Kakuro because Sudoku requires no math at all. But hard Kakuro and hard Sudoku are comparable in challenge. If you enjoy arithmetic and logic together, Kakuro may be more satisfying. If you prefer pure logic with no calculation, Sudoku is your puzzle.
Which Should You Try?
Start with Sudoku if you are new to logic puzzles. The rules are simpler and the learning curve is gentler. Once you are comfortable with Sudoku, give Kakuro a try. Many puzzlers enjoy both. They exercise slightly different parts of your brain.