What motif is Hugo trying to develop by repeatedly contrasting the two barricades, Saint Antione and the Barricade du Temple?
I tend to think that fundamental motif that Hugo is wishing to exploit through the comparisons of both barricades is how France, specifically Paris, was trapped between two intensely warring forces. There was little in way of negotiation between both. Both barricades represent fundamentally divergent paths of the good. This can be seen in their architecture. Hugo describes the architecture of the barricade at St. Antoine as the embodiment of energy and zeal, without much in way of aesthetic beauty or rational thought:
The Saint-Antoine barricade was tremendous; it was three stories high, and seven hundred feet wide. It barred the vast opening of the faubourg, that is to say, three streets, from angle to angle; ravined, jagged, cut up, divided, crenelated, with an immense rent, buttressed with piles that were bastions in themselves throwing out capes here and there, powerfully backed up by two great promontories of houses of the faubourg, it reared itself like a cyclopean dike at the end of the formidable place which had seen the 14th of July.... The mass beside the atom; the strip of ruined wall and the broken bowl,--threatening fraternization of every sort of rubbish. Sisyphus had thrown his rock there and Job his potsherd.
There is a chaos in construction that reflects the spirit of "Revolution" that Hugo attributes as an intrinsic part of its creation. In contrast to this chaos exists the intricate and architectural superiority of the barricade at the Rue du Temple. It is here where one sees the incompatibility between the revolutionaries and the Status Quo:
This wall was built of paving-stones. It was straight, correct, cold, perpendicular, levelled with the square, laid out by rule and line. Cement was lacking, of course, but, as in the case of certain Roman walls, without interfering with its rigid architecture. The entablature was mathematically parallel with the base. From distance to distance, one could distinguish on the gray surface, almost invisible loopholes which resembled black threads. These loopholes were separated from each other by equal spaces.
The motif of both of these forces standing in strict opposition to one another is reflected in the architectural design of each barricade. It is in this where Hugo draws demarcation, suggesting that there can be no resolution to the sides and interests that both forces have deemed as vital to their cause. It is with this backdrop that conflict becomes inevitable and a battle in which only one side can emerge victorious.