differences between various --direct commands

For adding a custom iptables rule using firewall-cmd, I'm having a difficult time understanding the difference between these: --direct --add-rule --direct --passthrough --direct --add-passthrough The manual explanation sounds the same for all three. There must be a reason to have each one, they have to be different, can you help me know which I am to use? ------------------------------------------------- ONLY AT VFEmail! - Use our Metadata Mitigator to keep your email out of the NSA's hands! $24.95 ONETIME Lifetime accounts with Privacy Features! 15GB disk! No bandwidth quotas! Commercial and Bulk Mail Options!