why plot of ''To Workspace'' of matlab does not fit the scope of simulink?
You are plotting discrete time points using the plot function which will simply join the dots. The data points don't give any indication of what is going on between the points.

The other graph which I presume is from Simulink will be using a sample-hold plotting such that it will plot the same value over time until it changes. This is equivalent to the stairs function in MATLAB.

Which one is "correct", who knows, only you know what the system you are measuring. The two plots are just two different ways of displaying the data.