Kakuro vs. Sudoku: What's the Difference?

Kakuro and Sudoku Definitions
Kakuro
(games) A type of number puzzle, similar to a crossword but with numbers. Each "clue" is the sum of the digits to be placed in its group of squares, and no digit can be repeated within a group.
Sudoku
A puzzle in which a grid consisting of several regions is to be filled with numbers so that every row, column, and region contains only one instance of each number. The most common format is a grid of nine rows and columns that are divided into nine smaller regions of three rows and three columns into which the numbers 1 through 9 must be placed.
Sudoku
A type of pencil puzzle played on a square grid, requiring each of the columns, each of the rows, and each of the subregions (called "boxes" or "regions") to contain the lowest whole numbers up to the dimension of the puzzle, usually 1 to 9, once each. The subregions are rectangular or square except in variants.