Can anyone tell me what the differences are between Carbonetic's twin disc "Standard" (street and track) and "Type R" (drag) clutches?

It's not the pressure plate because both Standard and Type R come with either an 1100kg or 1350kg pressure plate. It's not the lw flywheel either since they both come with it as well.

Really impatient right now and Carbonetic is closed today and maybe Monday since it's MLK Day...What could "drag" mean in comparison to "street and track", how different could it be.

Here's the part # I'm talking about: ACN23285L-14 (under Sykline - twin disc)

And here is Carbonetic's listing: http://www.carbonetic.net/match/others_nissan.html