Problem with boolean difference

Hello everyone,

I have a problem with a Boolean difference. Indeed, I exported 2 objects aligned in STL and I would like to make the Boolean difference but I can not. At best it completely removes the element to subtract without making the Boolean difference.
Could you help me or give me some advice to make this difference?

Here are the files with which I tried to make this difference.
CAD must be subtracted from Measure
CAO STL.stl (1.0 MB)
Mesure STL.stl (19.1 MB)

CAD = red
Meassure = blue

do you want to see some deviations ?
check the _PointDeviation command

or use another software that is specialised on quality control / scan data inspection …

result of pointdeviation
quit sure that any mesh-boolean will fail with this nearly matching points…
(if you really need Mesh-booleans, try new Rhino 8 (as a 90 day trail) - it has rewritten mesh operations)

The goal is to get the volume of the first file called Mesure STL not belonging to the CAD, regardless of the method. Do you have any idea how to do that?

In Rhino 8 you can mesh boolean one from the other. However, if you look carefully at @Tom_P 's image you will see that the two items are not perfectly aligned. Is this deliberate? It has the effect of creating a messy, unclosed mesh which, I suspect will not be useful.

Alignment is done in the best possible way as there are always differences between the measured parts and the original CAD.
I just tried to make a boolean difference with Rhino8 and it seems to work unlike Rhino7