disseminated is like the margerine content in the sponge part of a sponge cake. Massive is like the cream in the middle bit. If you drilled through a victoria sponge you might well not end up with as much creamy bit as is actually present in the whole.
I tried this experiment earlier in my kitchen and can report that the creamy bit assays underestimate the reality of the victoria sponge in question.
Who needs SRK?
The NE zone intersection included both massive and disseminated evidence of moly, btw.