Hey Jay,
The "3.10" information within the first column is referencing to the same image with the only difference that the "new" kernel version - 3.10 - is being instead used of the old on in the previous version.
More information regarding this change can be read here.
This release introduces the new 3.10 kernel for Security Gateways. It extends support for new platforms and offers a significant performance improvement in cloud environments.
Check Point R80.30 with Gaia 3.10 is now available. For more information, refer to sk152652.
For Security Management Server, the new 3.10 kernel is already part of Check Point Main-Train release starting from R80.20, and is supported on all Security Management platforms (see R80.20 Release Notes).
Regarding the other two options:
R80.20 Fresh Install and Upgrade for Security Gateway and Standalone
=> this is the CPuse package which allows you to upgrade or freshly install an already configured and running security gateway - therefore the .tgz file ending
R80.20 Gaia Fresh Install for Security Gateway and Standalone
=> this simply is an .iso file which allows you to install and set up a new, fresh, security gateway which previously did not have any CP software installed
Regards,
Maik