The role of localized defect centers and continuous gap states distribution in photoluminescence, photoconductivity, and photoresponse time dependence of diamond films have been analyzed for different film morphology and grain orientations. Sharp spectroscopic features related to impurity centers or broad components associated with continuous distribution of gap states prevail in the spectra depending on film microstructure and deposition technique. It is shown that defects, either localized or continuously distributed, reduce carrier lifetimes and slow down carrier transport by trapping effects. The observation of metastability effects after UV illumination giving an increase of subgap photoresponse is also reported.