M. D. Bown explains the different kinds of similarities he found between the Spaulding manuscript and the Book of Mormon.
M. D. Brown, "One Hundred Similarities Between The Book Of Mormon and The Spaulding Manuscript," 1937, University of Utah Marriott Library Special Collections, 2-4
One might suppose that in a study of this type there should exist a number of parallels between the two works, and when these had all been located, no additions could be made. This is only very broadly true, unfortunately, and has caused much difficulty throughout. What shall one consider as a genuine parallel? Reynolds cites as a dissimilarity that the Roman party landed on the east coast of the American continent, while the Nephites landed on the west coast. Is it legitimate to use the fact that both landed on the American continent as an item of similarity? Again, the Mormon record was alleged to have been written in "reformed Egyptian," the Spaulding tale in Latin. Is it legitimate to cite that both records required translations itemized are of this nature--two variations of exactly the same general idea, the same incident, or the same type of circumstances--and this has been regarded as sufficient reason for including many items.
A second group of parallels includes those that are scarcely peculiar to both works and are relatively trivial in themselves, but in the aggregate, it is felt, approach significance. Thus is listed the fact that both records mention many rivers and bodies of water--obviously trivial--and should one mention that their were families, marriages, eating by the people, that night followed day, and the like? No fixed rules has been followed in these instances; most type have not been included, and perhaps many that were could well have been ommitted. Still a third group of similarities might have been included, that is, those based upon an "absence of mention." For example, it is obviously witless to cite that neither works mention railroads, but what shall we say to the fact that both works are, for example, exceedingly vague as to topography and geography, both frequently leave a character "in mid-air," introduce people without any antecedent history, were originally written without verse division, and the like? None of this type has been included.
Evidently, then, one might extend the list of parallels well-nigh indefinitely--or attenuate it to near zero, depending upon the notion of what constituted "similarity" one preferred to adopt. And this, no doubt, would depend considerably upon one's personal prejudices, difficult to obviate where religious beliefs are concerned. Under the circumstances, the present writer has been very generous in listing similarities, depending largely on direct quotations, item for item, with only minimum comment, preferring others to be the judges as to whether the suggested parallels represent true similarities or not.