The LDS and the JWs are both sectarian fundamentalists of Christianity that take a literalist view of the bible that are less than 200 years old, formed in the United States of America during a time of growth, expansion, arrogance, and with animated evangelism follows a leader with a “new” interpretation of the scriptures granted to him exclusively by god.
This puts them in a position to be remarkably similar in their view of the ancient civilization in which the bible was written, taking it by-the-letter as inspired historical fact, and is reflected in current civilization with their arrogant refusal to budge on social issues of women's equality, homosexuality, and humanitarianism.
They are both believers in the strict adherence to the “last days” concept and apply such to their own lifetimes, whatever that lifetime may be. They are both hierarchical religions structured in the same format as the patriarchal families of the old testament and that of Paul's direction in the new testament. They do not necessarily resemble the first century churches as they were a mess filled with people who were trying to balance who they were as a people (Jews) and who they were as a faith (belivers in Christ). So the first century Christians were all over the place. Also, there were MANY forms of Christianity in the first century and each remained seperate for at least 200 more years.
Both the LDS and the JWs feel that their way is the only way to salvation, and that anyone that disagrees with them will die at Armageddon... which is due at any moment.
Structurally and systematically, they are pretty much the same religion. Dogmatic differences are many, but that comes with the invention of a new religion. They focus more on how they are different from everyone else and fail to see how similar they are. From an outside vantage, they are not. Yes, their belief may be different, but they function in the same format and the end result is exactly the same: Nice people who appear to do good, but drowning in a sea of self-superiority with the “fact” that they are the one true religion.
There is nothing new under the sun... and these two barely toddler religions on the world's scene are hardly exceptions.