Digital BW, The Print

I could sear that I have seen this question asked and answered, but cannot
find it.

What is the essential difference between these two papers (using K3 inks)?
I've had both, but not at the same time.  I seem to recall that semigloss
is a little thicker, perhaps?  But not seeing them side by side, my
perception of the two is that they are the same.  --except it seems there
are more choices for packaging in the luster - 20, 50, 100, 250 sheet packs,
etc.

Can anyone give me a quickie comparison?


[Non-text portions of this message have been removed]