Answer:
a parameter is fixed over time, while an exogenous variable is allowed to change over time.
Step-by-step explanation:
A parameter can be defined as a value that can be passed to a function. Thus, a parameter refers to a value that must be passed into a function, subroutine or procedure when it is called.
This value can be passed to a function either by reference or by value.
Basically, parameters can serve as a model for a function; when used as an input, such as for passing a value to a function and when used as an output, such as for retrieving a value from the same function.
A variable can be defined as a placeholder or container for holding a piece of information that can be modified or edited. Thus, a variable stores information which is passed from the location of the method call directly to the method that is called by the program.
An exogenous variable can be defined as a that's independent of other variables in a system i.e it's not affected by other variables.
This ultimately implies that, the difference between a parameter and an exogenous variable is that a parameter is fixed over time, while an exogenous variable is allowed to change over time and as such it has a relationship with other variables in a system.