Ubuntu – df -h shows different size on nfs client than on nfs server

I am running ubuntu 14.04 LTS on two servers in AWS. One is running nfsd and the other is running the client. I made a 250GB EBS volume and shared it, then I went onto the client and mounted it.

Here's the server

ubuntu@nfs:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1      7.8G  954M  6.4G  13% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev            1.9G   12K  1.9G   1% /dev
tmpfs           377M  340K  377M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            1.9G     0  1.9G   0% /run/shm
none            100M     0  100M   0% /run/user
/dev/xvdb       250G   33M  250G   1% /mnt/nfsstore

Here's the command I ran on the client

sudo mount -t nfs -o proto=tcp,port=2049 nfs.prod:/ /mnt

Here's the client

ubuntu@web11:~$ df -h
Filesystem    Size  Used Avail Use% Mounted on
/dev/xvda1    7.8G  1.1G  6.3G  15% /
none          4.0K     0  4.0K   0% /sys/fs/cgroup
udev          1.9G   12K  1.9G   1% /dev
tmpfs         377M  348K  377M   1% /run
none          5.0M     0  5.0M   0% /run/lock
none          1.9G     0  1.9G   0% /run/shm
none          100M     0  100M   0% /run/user
/dev/xvdb      20G   44M   19G   1% /var/www
nfs.prod:/    7.8G  954M  6.4G  13% /mnt

I was expecting 250G to be available at /mnt/nfsstore – is this a display bug, or can I expect only 6.4GB of space available?