Defining the covariant derivative is essential for understanding how to differentiate tensors on manifolds, as simple partial derivatives do not yield tensors in general. The covariant derivative accounts for the curvature of the manifold, allowing for intrinsic differentiation along curves on the surface. Unlike the Lie derivative, which does not maintain tensorial properties, the covariant derivative ensures that the results remain consistent with the manifold's geometry. This is crucial for formulating differential equations in the context of fields on manifolds. Understanding these concepts is vital for advanced studies in differential geometry and theoretical physics.