Epitaxial lateral overgrown GaN structures, oriented along different crystallographic directions ([1120] and [1100]), using different mask materials (SiO2 and W), were comprehensively characterized by cathodoluminescence (CL) microscopy and micro-Raman spectroscopy. CL microscopy directly visualizes the significant differences between the overgrown areas on top of the SiO2-mask and the coherently grown regions between the SiO2-stripes in quantitative correlation with micro-Raman spectroscopy mapping the local strain and free carrier concentration. The overgrown GaN shows a partial strain relaxation and a high carrier concentration strongly broadens the luminescence. A strong impurity incorporation is evidenced in the coalescence regions. In contrast, the local luminescence from the areas of coherent (0001) growth is dominated by narrow excitonic emission, demonstrating its superior crystalline quality.