riddle vs puzzle

riddle and puzzle both are nouns.

Word	Noun	Adjective	Verb	Adverb
riddle	Yes	No	Yes	No
puzzle	Yes	No	Yes	No

As verbs, puzzle is a hypernym of riddle; that is, puzzle is a word with a broader meaning than riddle:

Other hypernyms of riddle include amaze, baffle, beat, bewilder, dumbfound, flummox, get, gravel, mystify, nonplus, perplex, pose, stick, stupefy, vex.

riddle (noun)	puzzle (noun)
a coarse sieve (as for gravel)	a game that tests your ingenuity
a difficult problem	a particularly baffling problem that is said to have a correct solution

riddle (verb)	puzzle (verb)
explain a riddle	be a mystery or bewildering to
set a difficult problem or riddle	be uncertain about; think about without fully understanding or being able to decide
speak in riddles
pierce with many holes
separate with a riddle, as grain from chaff
spread or diffuse through