The structural and optical properties of GaN nanowires (NWs) grown by catalytic and self-catalytic assisted vapor liquid solid approach using chemical vapor deposition (CVD) were reported. Liquid Gallium droplets were used as the nucleation centre for the growth of self-catalyst assisted NWs, while pre-deposited Ni and Au thin films were employed as the seed layer for the catalyst assisted growth on Si (111) substrates. Electron microscopy analyses reveal that the growth rates and densities of structural defects of the NWs strong vary with the nature of the catalyst. High resolution electron microscopy and selected area electron diffraction study exhibits a high crystalline quality of Ni-catalyst assisted GaN NWs, while self-catalytic NWs contain defects such as stacking faults and cubic inclusion. Temperature dependent photoluminescence on the ensembles of NWs illustrate the absence of characteristic yellow luminescence band of GaN for Ni-assisted vapor-liquid-solid (VLS) approach implying the high optical quality of GaN NWs by CVD. The results show that the quality of self-catalytic GaN NWs grown by CVD is yet to be improved for device applications.