Comparative visualization has successfully been applied to a variety of fluid dynamic problems. Most applications rely on image level comparison such as experimental flow visualization versus computational flow imagery (CFI) which tries to simulate optical image acquisition in flow testing. When differences become difficult to distinguish or once a quantitative result is required, data level comparison provides powerful means to visualize data from multiple sources. Data level comparison and visualization turns out to be an essential tool in modern aircraft design projects.It is already successfully applied in the geometric preprocessing stage and the CFD analysis and will serve for comparison with experimental data as well.