The mechanical properties of metallic materials are essentially controlled by their microstructure. Especially, by generating ultrafine-grained microstructures, materials with unique characteristics can be produced. Compared to their conventional, coarse-grained counterparts, these materials often exhibit a significantly increased strength. Equal-Channel Angular Pressing (ECAP) is an established method to achieve considerable grain refinement. While there is substantial knowledge about ECAP of bulk materials, using similar processing approaches for thin sheets results in several issues (e.g., buckling, excessive friction, surface cracking). In this contribution, we consider and compare two fundamentally different approaches for ECAP of thin AA5083 aluminum alloy sheets: (i) deformation of single sheets in a custom-built ECAP die; (ii) ECAP of a stack of sheets in a conventional die. The evolution of microstructure and grain size distribution during multiple ECAP passes is characterized by EBSD. The results reveal that the two different approaches lead to different characteristics in terms of local deformation and grain refinement. With an increasing number of ECAP passes severely deformed conditions show increased strength at room temperature and comparatively large elongations to failure, particularly at elevated temperatures. Based on these results we discuss the issues and evaluate the suitability of the different ECAP approaches for producing (ultra-)fine-grained sheet materials for further scientific research.