Question { FCI, 29650 }

what is the difference between logon group(tcode-smlg) and
rfc group(tcode-sm59)?

Answer

Logon load distribution allows you to dynamically
distribute the SAP users to application server instances.
You can increase the efficiency of individual workgroups by
setting up multiple logon groups that consists of one or
more application instances.

RFC groups, you can control which servers can be used for
parallel-processed jobs. An RFC group specifies the set of
allowed servers for a particular parallel-processed job.