A very general comparison comes to mind between these two brands. While Tecnica has about 5 different lasts shapes and Dalbello has only two, The Tecnicas generally have steeper angles while the Dalbellos are more upright in comparison. So to generalize again, the Tecnicas seem to be more suited for shorter statures and shorter lower legs using flatter delta bindings. There are many skiers who ski overflexed in these boots and need to reduce the delta angle under the boot. While the Dalbello seems more suited to a taller person with longer lower legs.
The above is just a general observation from experience with both brands. Either brand can be modified as needed for individual alignment needs.