So a method can be mimetic if using either finite difference or finite element method. It depends on the properties that it presents.
To be called mimetic, a numerical method should satisfy the following properties:
For example, a symplectic integrator is used to compute a numerical approximation to the ordinary differential equations that describe motion. The resulting approximation conserves energy.
A mixed finite element method applied to Darcy flows strictly conserves the mass of the flowing fluid.