sudoku vs puzzler

sudoku and puzzler both are nouns.

Word	Noun	Adjective	Verb	Adverb
sudoku	Yes	No	No	No
puzzler	Yes	No	No	No

As nouns, puzzler is a hypernym of sudoku; that is, puzzler is a word with a broader meaning than sudoku:

sudoku: a number puzzle in which the numbers 1 through 9 must be placed into a grid of cells so that each row or column contains only one of each number
puzzler: a particularly baffling problem that is said to have a correct solution

Other hypernyms of sudoku include mystifier, puzzle, teaser.

sudoku (noun)	puzzler (noun)
a number puzzle in which the numbers 1 through 9 must be placed into a grid of cells so that each row or column contains only one of each number	a particularly baffling problem that is said to have a correct solution