1. An apparatus which compares two modules each including one or more sentences written in a programming language, wherein: the modules are capable of including conditional statements written therein, wherein each of the conditional statements is one of the sentences, the conditional statement includes at least one of an executable-on-satisfaction statement and an executable-on-failure statement, the executable-on-satisfaction statement is the sentence that is executed when a conditional expression of the conditional statement is satisfied, the executable-on-failure statement is the sentence that is executed when the conditional expression is not satisfied, at least one of the conditional statements is capable of including the other conditional statement therein as at least one of the executable-on-satisfaction statement and as the executable-on-failure statement so that the conditional statements enable a hierarchization of the sentences, and the hierarchization of the sentences forms a specifiable hierarchical structure of the module; the apparatus comprises a storage device and a CPU which is configured to operate as a comparing device; the storage device stores two or more of the modules; and the comparing device obtains a first module and a second module, from the storage device, among the modules stored in the storage device, and creates a message which shows whether the hierarchical structure of the first module is identical to the hierarchical structure of the second module or not.