Explanation
Synchronization works in two modes:
Full Sync transfers all Security Gateway kernel table information from one cluster member to another. It is handled by the fwd daemon using an encrypted TCP connection on port 256.
Delta Sync transfers changes in the kernel tables between cluster members. Delta sync is handled by the Security Gateway kernel using UDP connections on port 8116.
References:

Explanation
Wire Mode is a VPN-1 NGX feature that enables VPN connections to successfully fail over, bypassing
Security Gateway enforcement. This improves performance and reduces downtime. Based on a trusted source
and destination, Wire Mode uses internal interfaces and VPN Communities to maintain a private and secure
VPN session, without employing Stateful Inspection. Since Stateful Inspection no longer takes place,
dynamic-routing protocols that do not survive state verification in non-Wire Mode configurations can now be
deployed. The VPN connection is no different from any other connections along a dedicated wire, thus the
meaning of "Wire Mode".

References:

Explanation/Reference: https://supportcenter.checkpoint.com/supportcenter/portal?
eventSubmit_doGoviewsolutiondetails=&solutionid=sk50840

Reference:
https://sc1.checkpoint.com/documents/R76/CP_R76_CLI_WebAdmin/84627.htm