@Jason:
Well, you are right, but it seems they are not well differentiated in your explanation. Dave link explains it clearly. The links I gave explain it too, but I guess you did not buy the articles I recommended (no wonder at U$28 each).
What I got is this:
Graining occurs by
friction with pavement. Actually, F1 tires are "dried" and after they lost the "liquid phase" they disintegrate.
Blistering occurs by
inner friction. The layers of the tire bend every revolution, they rub against each other, and this produces heat. This heat moves outward and separate the rubber from the inner layers of the tire.
So,
graining occurs at curves and braking/accelerating zones. You need to change the rubber or the asphalt to alleviate it.
Blistering occurs anywhere, as long as the wheel is rotating. You do not need friction with pavement for it to occurs. You need to change the inner structure of the tire or the heat carachteristics of the rubber to alleviate it.
Both are affected by tire pressure and load, as you can deduce, but I would guess that the blistering could be dimished if you inflate the tire, because it flexes less, but you will get more graining because you diminish the contact patch size.
If this is true, as Jason's post says, a blistered tire can happen easier on a high-speed circuit, with long straights and big radius curves, where the tire is rotating and flexing at high speeds while is hot.
A grained tire would be characteristic of a "chicaned and hairpined" circuit (I mean a short-straights and small-radius-curves circuit). Here the tire is used to brake and turn at relatively slow rpm's.
