1. A method for generating similarity coefficients between model elements when comparing a first data model having hierarchically organized first model elements and a second data model having hierarchically organized second model elements, comprising: first generating a plurality of inherent similarity coefficients for each pair of model elements, with each pair comprising a model element of said first model elements and a model element of said second model elements; second generating a plurality of structural similarity coefficients for each pair of model elements based on a similarity of subtree elements rooted by the element pair, whereby each pair of model elements is assigned an initial structural similarity coefficient; third generating a plurality of weighted similarity coefficients for each pair of model elements as a weighted function of said plurality of inherent similarity coefficients and said plurality of structural similarity coefficients; and for each pair of model elements, altering the similarity of said subtree elements rooted by the element pair if a function based on said weighted similarity coefficient of said element pair meets a predetermined condition.