Until now, the building of comparable databases for European cities has been made through two different approaches: - a bottom up process, from national to European level, relying on the collect of national delineations by European institutions (NUREC 1994, ESPON 1.4.3. 2007, Urban Audit 2009) - a top down process, which consists in applying the same criteria to the whole European space (e.g. Urban Morphological Zones, produced by the European Agency of Environment, 2000). In the latter case it is essential to submit the resulting objects to a validation process worked out by national experts or based on national databases. Our paper is a contribution to the validation of UMZ database, in order to make these morphological zones more operational for urban studies. We develop here a first expertise by comparing UMZ to French and Danish morphological agglomerations. We first introduce the methodological frame of this comparison, which has been thought to be transposed to other countries. This protocol has to consider semantic and geometric differences between databases. It leads to a few fittings in order to enable the integration of both UMZ and national urban databases. Then we develop the main results of the comparison made in France and Denmark, from both quantitative and qualitative points of view. The measure of key indicators underlines the convergence of UMZ and national databases (an average difference of +/- 5% for urban populations). However, in France some large cities are sometimes much more spread out in national databases than they are from UMZ source. These main types of differences in France can be due to specific types of settlement patterns (coastal or industrial conurbations, large city margins). It raises the issue of applying similar criteria in different territorial contexts. By improving our knowledge about UMZ and their use for urban studies, this expertise aims at constructing comparable databases and it follows practical goals. But it also tends to enlighten the specificities of some settlement patterns throughout Europe, in a more exploratory way.