NAS is known to be a device that will operate on data files. SAN is known to be a local network wherein different devices can become connected to it. SAN is known to be able to provide higher performance as compared to NAS. The file system of NAS will have a slower file system.
Do take note that it will be easier for a lot of people to create high-speed networks within NAS so it can still function properly. SAN will have some advantages over NAS in terms of easier management and also improving the current network infrastructure. Data can be easier to store at a file level.