Here is a link to the Wikipedia article. In brief, it says that “Jack Mormon” is a term that these days means a person who is Mormon in name only. That is, they identify themselves as Mormon and have positive feelings towards the church, but do not follow its commandments nor engage regularly in its activities. The other, perhaps more common term is “inactive”.
You are correct, I think, in comparing a Jack-Mormon to a lapsed Catholic. But the term “cafeteria Catholic” does not compare closely. Many cafeteria Catholics are quite active, but still pick and choose which commandments they will follow.
It would be more difficult for Mormons to be cafeteria Mormons, because the members watch one another carefully and report to their superiors (and everyone else usually) when someone is suspected of being “unfaithful”. The leaders then call the person in for counseling and sometimes discipline. I had personal experience with this when my non-LDS parents came to visit. I went to the store to buy some coffee to serve them, and a member of the ward observed me. She reported to the bishop that I was breaking the “word of wisdom”. The bishop called me in to his office to investigate whether he should take away my temple recommend. I explained the situation to him, and he counseled me to make my parents go without their morning coffee as a “testimony” to them. I did not follow his advice.