The difference between the Declaration of Independence and “What is the Third Estate?” is the inflammatory nature of the latter. The Declaration of Independence was written by the Americans in order to outline the grievances they had against the crown. They had no reason to expect any immediate retaliation by the king because the main body of the king’s forces was all the way across the Atlantic Ocean. Not only that but the king would not even hear about the document for months because of that distance. “What is the Third Estate?” was written under a different set of circumstances. The piece was written in France within easy reach of the French government and military. There was much more danger associated with a revolution on French soil because of the potential immediate response times.
The Declaration of Independence was written in a tone that inspired patriotism in the readers. This was because many of the citizens were still loyalists and wanted to remain a British colony. There was no need to incite the citizens themselves to rise up and fight the British because they were so far removed from the King. There was no need for the average citizen to take up arms against British soldiers. The same was not true of “What is the Third Estate?” Abbe Sieyes was well aware of the clear and present danger that accompanied the proliferation of this document, both to the author and to the citizenry as a whole. He knew that it would take much more forceful language in order to incite every citizen to take up arms, especially with the proximity of so much raw power nearby.
The difference between the two documents is mainly because of the context in which they were written. If the colonists of America had an entire army breathing down their necks they would have been less easy to rile up. An army is usually a pretty good deterrent. The fiery speech of Abbe Sieyes was necessary, however, because of the great danger that the French were up against.