database size changed after restoring using pg_restore

Hi
I am upgrading some databases from a PostgreSQL 9.2 server to a new PostgreSQL 9.6 server.

I used pg_dump and pg_restore for the upgrade.

This is the command I used to dump the database. I ran the command from the 9.6 server.
pg_dump -h 9.2server -j 16 --format=directory -f /pg_backup/backup/dump/mydb-20171108.dmp -U postgres -W mydb

This is the command I used to restore the database on the 9.6server.
pg_restore -j 16 -C -d postgres /pg_backup/backup/dump/mydb-20171108.dmp

Everything appears ok, the dump and restore completed without and errors.

But when I listed the size of the database (postgres=# \l+) between the 9.2 and the upgraded 9.6, they were different.

on 9.2 it was 3776 MB
on 9.6 it was 1570 MB

I also did a few more databases using the same steps and they all appeared to be smaller. Is that normal?

Regards
Dylan