Two series of diamond films grown-at different temperatures-by two chemical vapor deposition (CVD) methods, i.e., hot filament (HFCVD) and microwave-plasma (MPCVD), were investigated. Raman spectroscopy and scanning electron microscopy were employed to perform a study of both crystalline quality and phase purity of the films grown by the two techniques. It was found that high phase purity can be attained by both methods. However, at high temperatures, the MPCVD technique produced films with higher crystalline quality as compared to those grown by HFCVD. Finally, in order to shed some light into the mechanisms responsible for the lower crystalline quality observed in the HFCVD films, a study based in the phonon confinement model and stress was accomplished.