pull someone's leg vs hoax

pull someone's leg is not a noun while hoax is a noun.

Word	Noun	Adjective	Verb	Adverb
pull someone's leg	No	No	Yes	No
hoax	Yes	No	Yes	No

As verbs, pull someone's leg and hoax are synonyms defined as:

Other synonyms of pull someone's leg include play a joke on.

pull someone's leg (noun)	hoax (noun)
	something intended to deceive; deliberate trickery intended to gain an advantage

pull someone's leg (verb)	hoax (verb)
subject to a playful hoax or joke	subject to a playful hoax or joke