NAS provides better support for heterogeneous operating system environments.
NAS is often the preferred solution for file-sharing applications, because NAS appliances implement OS-independent file systems.
SANs are optimized for block-level traffic, so they are often the preferred solution for databases. However, NAS vendors are beginning to find ways to increase the performance of NAS solutions for database applications.
NAS/SAN hybrid solutions are also available: NAS heads provide a gateway to SAN-based storage resources.