Chromosomal Inversions are rearrangements of the gene order within a single chromosome, resulting from incorrect repair of two breaks. The amount of chromosomal material remains the same, but recombination within the inverted region leads to unbalanced gametes. Also, due to new order of gene, new nascent protein may be produced.
There are different classes of inversions, which could be based on whether or not the centromere is involved. An inversion in which the centromere is located outside of the inverted region is called a paracentric inversion.
As seen in the figure below:
An inversion in which the centromere is located within the inverted region is called a pericentric inversion.
See the picture below:
Pericentric Inversion is usually more lethal due to area of coverage which usually leads to change in structure.