The type and scale of internal diversification are the main characteristics of metropolitan areas. There are some agglomerations where areas differ only slightly and some where territorial disparities are significant. The question is whether this internal diversification is a factor which stimulates spatial and economic development? I n other words, which strategy should be chosen in terms of planning solutions: the egalitarian strategy targeted at equalisation or the one focused on using the competitive advantage of diversification? These questions are related to the problem of diagnosing the diversity of metropolitan areas.