They are both cults, so it's not surprising there are similarities. While their individual beliefs are different, the culture is the same because cults use the same basic manipulations.
Controlling your time by having lots of meetings and volunteer requirements so you don't have too much time to think.
Exclusivisim, claiming to be the only route to salvation.
Deception, hiding their history and practices. The JWs lie about their failed date predictions, The Mormons lied about Joseph Smith having multiple wives and although they have recently admitted as much I doubt they are honest about his various scams, he was just a con artist that got lucky.
Fear and intimidation, saying that you must do everything they tell you or you will not gain salvation. Jehovah's Witnesses fear being disfellowshipped and dying at the big A, Mormons fear going to hell.
Love bombing and relationship control. The JWs are by far the worst because of Disfellowshiping, but both groups discourage you from having friends or getting married outside the group.