That question makes no sense. This is like what is the difference between a car and an answering machine.
SSL is a transport level security.
IPMI is a remote control protocol. It may, btw., utilize SSL to protect the data in transit.
When was the last time you used SSL directly to install an operating system? Which part of the SSL standard allows you to turn a computer on or off?
Does the Supermicro IPMI Tool CLI allow access to the terminal on the head
node?
Consider occcasionally reading documentation. You have a lot of lacks of fundamentals that are clear aftethe first pages.
From what I know, SSL is simply access to the terminal of the head node and
IPMI is linked to the actual hardware of the head node, but that is
all.
"that is all" is sceaming ignorant. From what I know a rocket just burns fuel and "that is all". When you ahve to manage computers in a remove location or do not want to spend all day in data center environments (loud, cold) and are responsible for a lot of computes, "that is all" is exactly what you need. In fact "that is all" (access to the actual hardware) is what SSL is not providing and what IPMI is made for.