I believe you mean the "reticle" or aiming element of the scope.
In a variable magnification FFP or "first (or front) focal plane" scope, the reticle and object increases and decreases in size as the magnification increases and decreases.
In a variable magnification SFP or "second (or rear) focal plane" scope, the object in the scope increases and decreases in size as the magnification increases and decreases... but the reticle does not.
What Leupold says about the differences.
C