Months ago when I sat down with the 749 890 and 336 patents, I became overwhelmed trying to sift thru the mumbo-jumbo of what was what vs. the other, adnauseum.
From what I understand, the difference is in the secondary clocking one variation operating under an Asynchronous manner, the other operating synchonously.
That was enough of a difference for me to use that as an identifier...perhaps I over simplified.
Regards.