Autofs , is auto mounting filesystem on demand like when EVER you need it.
NFS is like mounting a complete partition remotely and you will have availability of whole content of the partition.
But there are few advantages with autofs over nfs.
Advantages of AutoFS :
Shares are accessed automatically and transparently when a user tries to access any files or directories under the DESIGNATED mount point of the remote filesystem to be mounted.
BOOTING time is significantly reduced because no mounting is done at boot time.
Network access and efficiency are IMPROVED by reducing the number of permanently active mount points.
Failed mount requests can be reduced by designating alternate SERVERS as the source of a filesystem.