Matlab and Scilab are both used for performing numerical computation and simulation. The difference lies in the fact that Scilab is open-source. The source code for Scilab core and its various toolboxes are available for anyone. The code can be modified to build new features or toolboxes. The other major difference is that Scilab is available free of cost. Nobody has to pay any money to download and install Scilab. In terms of syntax and functions, both are quite similar.