What is the difference between "10%" and "10 percentage points"?

[Nykeriab]

Throughout the game I've seen a few dozen things use these, and they're probably not interchangeable, but what is the difference? For example, in a Soul Tree, I see:

• Block Rate Up - Boosts Block Rate by 10%
• Block Rate Up - Increases Block Rate by 15 percentage points.

A quick read of those would lead me to believe they're the same effect, but what is the difference here?

[nishika]

As explained in comment, the first one multiplies the statistic by the value, while the second adds a flat value to the statistic.

Example with 2 accessories (one gives block rate, the other physical def, but the formulation is different).

• This first one boosts block rate by 32%. As you can see, I get a bonus of 32% of 27 = 8% block rate (rounded down, since 27 * 32% = 8.64).

• This second one increases my physical defense by 6 percentage points. As you can see, I get a flat increase from 48% to 54%.

It works the same with gems and the Soul tree.