chess problem vs mystifier

chess problem and mystifier both are nouns.

Word	Noun	Adjective	Verb	Adverb
chess problem	Yes	No	No	No
mystifier	Yes	No	No	No

As nouns, mystifier is a hypernym of chess problem; that is, mystifier is a word with a broader meaning than chess problem:

chess problem: a puzzle set by somebody using chess pieces on a chess board, that presents the solver with a particular task to be achieved.
mystifier: a particularly baffling problem that is said to have a correct solution

Other hypernyms of chess problem include puzzle, puzzler, teaser.

chess problem (noun)	mystifier (noun)
a puzzle set by somebody using chess pieces on a chess board, that presents the solver with a particular task to be achieved.	a particularly baffling problem that is said to have a correct solution