All is supporting all (gives no negatives to your combat style), Hybrid I think is the same except it gives boost to the combat style you're using if it's apart of the Hybrid choice, since Hybrid is 2 styles and not all 3.
But also I have no clue, I'm just judging based off what a hybrid use to be back in the day.
On my Mini-Kay atm, I'm using (for armor) a Reinforced Slayer helm [all], Dragon rider body [all], Dragon rider chaps [all], Warpriest of Arma boots [Hybrid] and Mystic gloves [magic] (only ones I have ATM, don't mock me!)
My block percentages against a level 100 target (arbitrarily chosen round number)..
http://puu.sh/7TOIp.png
If I remove the gloves (the only non-Hybrid/All item), the block chances all balance out to 57% .. So it seems that both Hybrid and All class items contribute equally to all three styles in terms of defence
Both All and Hybrid give no offensive penalties for the Body/Legs/Helm, either