First, let me tell you about both NFS and HDFS:
NFS (Network File system): A protocol developed that allows clients to access files over the network. NFS clients allow files to be accessed as if the files reside on the local machine, even though they reside on the disk of a networked machine.
HDFS (Hadoop Distributed File System): A file system that is distributed amongst many networked computers or nodes. HDFS is fault tolerant because it stores multiple replicas of files on the file system, the default replication level is 3.
The major difference between the two is Replication/Fault Tolerance. HDFS was designed to survive failures. NFS does not have any fault tolerance built in.
Benefits of HDFS over NFS:
Other than fault tolerance, HDFS does support multiple replicas of files. This eliminates (or eases) the common bottleneck of many clients accessing a single file. Since files have multiple replicas, on different physical disks, reading performance scales better than NFS.
Hope this will help!