Convergence estimates for some composition operators

There are different methods available in literature to construct a new operator. One of the methods to construct an operator is the composition method. It is known that Baskakov operators can be achieved by composition of Post Widder Pₙ and Sz\'asz-Mirakjan Sₙ operators in that order, which is a discretely defined operator. But when we consider different order composition namely Sₙ Pₙ, we get another different operator. Here we study such and we establish some convergence estimates for the composition operators Sₙ Pₙ, along with difference with other operators. Finally we found the difference between two compositions by considering numeric values.