pitfall vs difficulty

pitfall and difficulty both are nouns.

Word	Noun	Adjective	Verb	Adverb
pitfall	Yes	No	No	No
difficulty	Yes	No	No	No

As nouns, difficulty is a hypernym of pitfall; that is, difficulty is a word with a broader meaning than pitfall:

pitfall: an unforeseen or unexpected or surprising difficulty
difficulty: the quality of being almost beyond one's ability to deal with and requiring a great effort to achieve a positive result

Other hypernyms of pitfall include difficultness.

pitfall (noun)	difficulty (noun)
a trap in the form of a concealed hole	an effort that is inconvenient
an unforeseen or unexpected or surprising difficulty	the quality of being almost beyond one's ability to deal with and requiring a great effort to achieve a positive result