In isotropic material the stress-strain equations are independent of location of the point.

In non-homogenous material the material constants are functions of coordinates.

The most general anisotropic material needs 36 independent constants to relate the six independent stress components to the six independent and strain at a point.

There are three independent material constant relating stresses and strains in isotropic material

The matrix relating stresses and strains for orthotropic material changes with coordinate transformation.

Principal directions for stress and strain are same for orthotropic material.

The Generalized Hooke’s law is valid for any orthogonal coordinate system for isotropic material.

The Generalized Hooke’s law is valid for non-homogenous, isotropic material.

Material volume does not change during deformation.

The maximum shear stress depends upon whether the point is in plane stress or plane strain.