For the solution of partial differential equations, which often also interacts with modeling of physical and engineering processes highly automatized environments are widely used. For the solution of physical problems only the respective differential equations with the respective parameters have to be given and a geometry has to be specified.
Ansys  is a professional approach which offers an unexperienced user approved numerical methods and discretization schemes for the solution of simulation problems at a physical level. Standard simulations can be carried out without deeper knowledge of the process of discretization and solution of the respective equations, whereas the main focus is put on user-interoperability. It can be integrated directly in a computer aided design and engineering process and offers methods which are generally approved and tested under a large number of circumstances.
For the development of new models and discretization methods these methods are generally not appropriate, because many settings which would have to be set are at a low level which requires deep insight into the numerical details of the simulation. This, however, contradicts the initial aim of providing a high level simulation tool.
General purpose computer algebra programs like FEMLab  offer different methods of high level access to differential equations. In contrast to Ansys, these frameworks are intended to solve the respective problems at mathematical layers, even though physical interpretations and add-ons exist.