Size difference KVM machine qcow2

So I have this KVM machine using qcow2 as image disk. I set 2TB as size but when I type du -h to get the real size of the disk image it shows 626GB on the host.

When I type df -h into the VM machine I get this:

[root@srv1 ~]# df -h

Filesystem Size Used Avail Use% Mounted on

devtmpfs 7.6G 0 7.6G 0% /dev

tmpfs 7.6G 0 7.6G 0% /dev/shm

tmpfs 7.6G 305M 7.3G 4% /run

tmpfs 7.6G 0 7.6G 0% /sys/fs/cgroup

/dev/mapper/centos-root 1.9T 139G 1.8T 8% /

/dev/vda2 1014M 194M 821M 20% /boot

/dev/mapper/centos-home 100G 33M 100G 1% /home

tmpfs 1.6G 0 1.6G 0% /run/user/998

tmpfs 1.6G 0 1.6G 0% /run/user/0

[root@srv1 ~]#

​

My question is: where do I find the ~486GB difference?

Is there any way that I can clean this difference and get my VM qcow2 disk image to be ~140GB - size which is actually occupies? If so, how?