They don't supersede it, either.
Like the difference between "cession" and "session".
</net nanny>
“Supercede?” Some say that it goes back nearly 400 years as a misspelling and has become synonymous. I see “superceden” in Scot Middle English. I think I’ll let Jack McLamb (writer for the Family Guardian) slide on that one. Maybe he’s of more northern heritage than Latin-ish. —sometimes editor of net nannies.
[Little humor and mischief there. Thanks for the tip. ;-) ]