play a joke on vs pull someone's leg

play a joke on and pull someone's leg both are verbs.

Word	Noun	Adjective	Verb	Adverb
play a joke on	No	No	Yes	No
pull someone's leg	No	No	Yes	No

As verbs, play a joke on and pull someone's leg are synonyms defined as:

play a joke on and pull someone's leg: subject to a playful hoax or joke

Other synonyms of play a joke on include hoax.

play a joke on (verb)	pull someone's leg (verb)
subject to a playful hoax or joke	subject to a playful hoax or joke
deceive somebody