When studying the deformation behaviour of individual grains both the overall rotation of the crystallographic grain orientation and the subdivision of grains are of interest. Often grains of similar orientations are compared to study the effect of grain orientation vs. grain interaction. Such investigations reveal both similarities and differences. The present contribution gives an overview of a series of investigations, including transmission electron microscopy as well as three-dimensional x-ray diffraction on polycrystalline aluminium deformed to strains of 5-50%. The data are analysed focusing on the set of activated slip systems, more precisely whether the observed differences can be attributed to fluctuations in the relative activities of the same set of systems or whether activation of truly different systems is the origin of the variations between and within grains.