we produce some x86 boards with multistandard RS232/422/485 ports
and, to have this feature, in some of these boards, we use a
Fintek uart or superIO.
So this additional info "extra_name" can be useful for
a quick check if the serial ports are multistandard or not,
without any other investigations, but using only a simple command
like:
dmesg| grep ttyS
But as they work the same, why does it matter?
Yes you are right, by the user point of view, they are the same.
Userspace should not care here. Isn't there some other id you can
read/query for a hardware database tool to determine this?