NAS stands for Network-attached Storage and is generally regarded as the storage server which is file-level. It is connected to a server and is mainly responsible to make sure that the access has been provided to a group of users. When it comes to storing and accessing the files, all the responsibilities are beard by the NAS which can be a software or a hardware. It provides data access to a heterogeneous group of clients.On the other side, HDFS is a distributed file system and is actually based on commodity hardware HDFS is the primary storage system of Hadoop. It designs to store very large files running on a cluster of commodity hardware.