Comparing the French, German and English system of the formation of contract you can see some similarities like the need of an agreement in all countries. On the other hand in some areas there are eminent differences and the choice of different concepts. Often a concept is chosen to emphasize or to guarantee the protection of a particular value.
This can be seen in the model chosen for the way of apperception of the declaration of intent. In the French system the subjective system of the party has been chosen which protects the party pronouncing the declaration and the fact that the contract is effectively based on the free will of the parties. The objective approach chosen in the English system protects preferentially the addressee of the declaration and certainty in trade. But as the lack of protection of the not priory protected value can sometimes result in unfair situations, in some cases the system includes this protection by another mean.
The English Courts permit for example at least the rectification of the written contract when it is evident that the contract stipules something different than what is wanted by the parties, thus, more attention is paid to the will of the parties.
The case of gratuitous promises shows how often the same result is reached even if the concept is different. In English law they are not enforceable because there is lack of consideration, in Germany consideration doesn`t exist but gifts to promise of donation needs to be notarized to be valid. In both cases the protection of the donator is intended, only achieved by other means.
One can see that the choice of concept can be modified by many different factors. In consequence the protection of some values not priory emphasized in the beginning can in some cases lead to an approximation of the systems.