Hello Ester,

Oh no, a displacement map is like a texture.  It displaces at pixel level.
It is the texture -displacement that creates the "thickness".

Low or High Poly of the underlaying mesh are not important.
Both can have the same displacement features relative to the map size.

Only disadvantage is that the pixels only move in and out relative to the surface they are on.

Allow me to show an example of what I made in Poser5, when displacement maps first came out.

From left to right;

Object - Only Texture - Only Displacement Map - Texture and Displacement map
Click to enlarge

It is just the bare object.
All clothing you see comes from the texture and displacement maps.

Best of greetings, Tony

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!