Can NW6.5 SP6 be installed on a NW6.5 OES SP2 Server?

We have some NW6.5 SP5 which we have patched to SP6.
Just wondering if we apply NW6.5 SP6 to our NW6.5 OES SP2 Server?
(i.e a NW 6.5 OES Server that is currently patched with NW6.5 SP5/OES SP2)

Are they any differences between NW6.5 SP5 and NW6.5 OES SP2?
(as Novell don't currently list SP6 as OES SP3, unlike they did for
SP4/OES SP1 and SP5/OES SP2)