Mutation testing is a popular software testing technique, that inject artificial faults into the program and requires test cases to reveal these faults. In this paper, an experimental comparison is analyzed for different types of mutation testing tools in C Sharp language in .NET framework. Different mutation testing tools are giving different mutation score for a program. The objective of this paper is to investigate why the mutation score is different for different tools, and the scope of generating mutants depending on different types of operators. Four tools, such as, Visual Mutator, Cream, Ninja Turtles, and Nester are selected and applied to a program and analyze the outcome. Among these four mutation testing tools, Visual Mutator is better because of its higher mutation score, and it generates mutants for both common and uncommon standard operators and object level operators.