I think the Delica 98 refers to the FRN(synthetic)-handled version and the Delica II refers to the stainless steel-handled version.
There is a newer version of the Delica98. I believe you can see this one on the Spyderco Products page; the stainless one as well.
Dude,
That's the Delica 2001! Features a Boye dent on the front lock and a recessed area on the clip mount for sturdier handling! The SS Delica II is a fine piece as well!