In long-range situations, the performance of free-space optical (FSO) communication links is strongly impacted by atmospheric turbulence. In this paper we compare efficiency of turbulence effects mitigation in FSO communication links using spectral (wavelength) and spatial diversity techniques. Numerical analysis of both techniques is performed considering FSO communication setting with single-mode fiber-collimator transceivers. In the case of spectral diversity setting, the fiber-collimators are based on the use of photonic crystal fibers that provide single-mode operation for three distinct wavelengths (532, 1064 and 1550nm). In the spatial diversity communication setting, analysis is performed using multiple-transceiver configurations. Analysis includes both received signal's statistical and temporal spectral characteristics.