I'm rather confused, but the consensus has been 1978.
The honorable discharge looks like a form and only his name and the date are typed in.
After Rathergate, I sure don't want to assume these are real.
Unless Kerry signs Standard Form 180 and someone can examine certified copies or the originals, I wouldn't trust any form on his site. We've all been using the forms on Kerry's web site as our source, but I've never trusted them.
On the other hand, I've never seen any form with the date of 2001, so I think that is hogwash.
I've just gone back for a more careful gander, and will agree with your observation -- both dates are probably 1978. I still wonder why the discharges are described differently. The document that says only "Discharged..." was apparently prepared in 1985. I don't know when the other was prepared. The following link shows the history parts of the two documents (but clips the top and bottom, so no preparaton dates are visible):
http://www.tinyvital.com/BlogArchives/000802.html