Why does df show different data?

Question

Debian

Everyone, I
found this moment:
On the host system, I do lxc exec lxc_container_name df -h /, I get one value
In the container itself, I get a different value (in particular, two GB more)
Why can this be?

for containerization use lxd 2.0.5-0ubuntu1~ubuntu16.04.1
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04

Answer 1

Because 2 GB is occupied by images?

Answer 2

A sparse df file shows the actual size, but for example the ls command will show an unreal one (full size of sparse files)