The formation of leaf or the leaves are known as the foliation.
Foliation is the repetition of the metamorphic rocks. Every layer is like thin sheet of paper which a metre thickness. It is a sheet like planar structure.
Foliation is constructive process
exfoliation :
Exfoliation is the removal off the bone, rock or can say minerals.
And when it comes to exfoliation it is the removal of the outer layer may be due to some mechanical or chemical means.