Well, first keep in mind that what you are referring to is the transition between the first book and the second book in what is usually referred to as Bradford's Of Plymouth Plantation. Where the first book is about the Reformation in Europe (and especially in England in regards to the Church of England) and what got the colonists on their way, the beginning of the second book is primarily about the possibility of new government in the new world. In chapter 11 (the first chapter of the second book), the structure changes specifically in reference to before leaving England vs. being en route to the new world.
In this eNotes Educator's opinion, the first book deals with philosophy and the second book, which starts with chapter 11, deals with government. The specific dates that are given for the first book are 1550-1607. Any scholar of New England history can tell you that is before the first settlement happened. The structure of this part of Bradford's "history," then, is truly about the philosophy behind the move. For example, much of it before chapter 11 is about what the people were fleeing:
[We were fleeing] the persecutions of the heathen and their emperors. ... For many endured sundry kinds of torment, often rackings and dismembering of their joints [as a result of their ideas].
In chapter 11 (the beginning of the second book), Bradford suddenly changes the structure by returning to specifics about the settlers still on the boat and before they land at Plymouth Rock.
In taking this different structural turn, Bradford begins speaking about the new possible government. The pilgrims on the Mayflower discussed their ideas of government as they traveled. In fact, they already had a government set up before reaching the New Land. Then again there were the "discontented and mutinous" strangers who ascertained that they would be free once they landed and not have to follow any rules of this new government. These "strangers" claimed "Virginia" as their own. The rest of the chapter is about the "New Government" of "New England" as proposed by the loyal subjects of James I of England.
In conclusion, the structural changes between chapters 10 and 11 are the structural changes conducive to the difference between books 1 and 2 in Of Plymouth Plantation. In short, these changes are about thoughts before the voyage vs. government plans during the voyage by boat to the New World.