OK - I feel dumb, but what's the difference? Should I care? Thanks!

post consumer are items that have been through the cycle. In other words, has been producded and used (such as paper you are writing on and then goes to the recyler).
To explain regular recycled paper i will use an example. Lets say I'm a paper manufacturer and I put 3 holes in my paper so tehy can go into binders. Regular recycling is taking that paper from teh holes and using that in paper. So its not really recycling items that are used its just recycling from the manufacturing process.
I hope that wasnt too confusing :)
As Mimetic explained, non-post-consumer recycled paper is remnants from paper production itself, versus coming from paper products people have used and put in the recycling bin.
The paper industry often prefers pre-consumer waste because it's easy to collect and not contaminated. But when post-consumer waste isn't used, it ends up in the landfills. To make recycling count, we need to buy products made from post-consumer recycled materials.
So when you are shopping around, the higher the percentage of post-consumer waste, the better!
:)