curl vs flex

curl and flex both are nouns.

Word	Noun	Adjective	Verb	Adverb
curl	Yes	No	Yes	No
flex	Yes	No	Yes	No

As verbs, flex is a hypernym of curl; that is, flex is a word with a broader meaning than curl:

Other hypernyms of curl include bend.

curl (noun)	flex (noun)
lock of hair in the shape of a spiral or curl	the act of flexing
a round shape formed by a series of concentric circles (as formed by leaves or flower petals)

curl (verb)	flex (verb)
form a curl, curve, or kink	cause (an object) to assume a crooked or angular form
play the Scottish game of curling	bend a joint
twist or roll into coils or ringlets	form a curve
wind around something in coils or loops	contract
shape one's body into a curl	exhibit the strength of