puzzler vs word square

puzzler and word square both are nouns.

Word	Noun	Adjective	Verb	Adverb
puzzler	Yes	No	No	No
word square	Yes	No	No	No

As nouns, word square is a hyponym of puzzler; that is, word square is a word with a more specific, narrower meaning than puzzler:

puzzler: a particularly baffling problem that is said to have a correct solution
word square: a puzzle where you fill a square grid with words reading the same down as across

Other hyponyms of puzzler include sudoku, acrostic, chess composition, chess problem.

puzzler (noun)	word square (noun)
a particularly baffling problem that is said to have a correct solution	a puzzle where you fill a square grid with words reading the same down as across