I believe those are upgrade files only for upgrading from 2.0.7.0-1 and 2. So you don't have to download the full install, just the files needed to upgrade.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
What are these files for?
xoops-2.0.7.x_to_2.0.7.3.tgz
xoops-2.0.7.x_to_2.0.7.3.zip
(also posted here: http://dev.xoops.org/modules/newbb/viewtopic.php?topic_id=684&forum=37)
I believe those are upgrade files only for upgrading from 2.0.7.0-1 and 2. So you don't have to download the full install, just the files needed to upgrade.