Actually it takes more work (or lines of code) to define a Simulink.Parameter. But it has more capabilities.
It can define Min and Max value. It can give warning when Value is out of bound.
It can specify Unit, potentinoally do unit consistency check.
Most importantly, it can specify "storage class". It is used for code generation which allow you to specify how code is generated, e.g. imported, exported, global, define, etc.
Simulink.Signal is similar.
Not all capabilities have been available, especially in earlier version of MATLAB.
a=Simulink.Parameter
open a
