Simulink is the platform for Model-Based Design that supports system-level design, simulation, automatic code generation, and continuous test and verification of embedded systems.
Key capabilities include: A graphical editor for modeling all components of a system.
The Simulink approach is based on time based and multi rate system.
SO that will be useful for HDL code generation.
Whereas, MATLAB is for the mathematical based algorithm development and which will not consider the time while in simulation (independent of time).
Simulink is graphical and more interactive to the user.
Simulink is a graphical extension to MATLAB for modeling and simulation of systems.
One of the main advantages of Simulink is the ability to model a nonlinear system, which a transfer function is unable to do.
Another advantage of Simulink is the ability to take on initial conditions.