As Ron mentioned earlier, there's no difference between two types of ports on transit node.
Although primary and secondary ports are configured on transit nodes, both port types operate identically as long as the transit node remains a transit node.
If the transit node is reconfigured as a master node, the configured states of the primary and secondary ports apply.
But in EAPS multiple ring topology, a shared port cannot be configured on an EAPS master’s secondary port.
So if you plan to change role of the node, you may change type of ports based on your implementation.