Difference between backpacks with same ability

I noticed that are many backpacks with similar abilities but with something extra.

For instance

• Gunner Pack: Reduces damage from enemy attacks + increases magazine size for all weapons, allowing agents to fire longer bursts.

• Guardian Pack: Reduces damage taken from all attacks.

So, is there some place that describes how much is reduced or in what percentage it's reduced?

In that specific case, I imagine the Guardian Pack reduces much more damage than the gunner pack because that's the only thing it does... but I don't want to walk around with a Guardian pack if the reduction of the gunner pack is exactly the same and Gunner also does something else!

I already searched here and here.

Solution 1:

According to this Xcom Wikia article, Gunner packs reduce damage by 10% while Guardian packs reduce damage by 20%.
Packs with multiple perks offer less effect while packs with only 1 perk give more bonus.