despite their different mathematical nature, what is the visual difference?

Probably this helps you:

**Add**

The Add expression takes two inputs, adds them together and outputs the result. This addition operation is performed on a per channel basis, meaning that the inputsâ€™ R channels get added, G channels get added, B channels get added, etc. Both inputs must have the same number of channels unless one of them is a single Constant value. Constants can be added to a vector with any number of inputs.

**Multiply**

The Multiply expression takes two inputs, multiplies them together, and outputs the result. Similar to Photoshopâ€™s multiply layer blend. The multiplication happens per channel, meaning that the R channel of the first is multiplied by the second; the G channel of the first is multiplied by the second, and so on. Both inputs must have the same number of values unless one of the values is a single float value.

I got those informations from here: https://docs.unrealengine.com/latest/INT/Engine/Rendering/Materials/ExpressionReference/Math/index.html#multiply Just take a look at the pictures, then you will understand it

@fighter5347 i think you missed the point of this thread.

http://cgtextures.com/content.php?action=tutorial&name=blendmodes

good tutor on photoshop blendmodes that work similar to these nodes, still very different but you get some idea

Wow, great article, thanks for sharing!

Short answer:

â€śAddâ€ť lightens

â€śMultiplyâ€ť darkens

Cheers,

Michael