is there a difference between the derivative of a function and the derivative at a point? If so please explain to me what it is

A derivative of a function is a function everywhere it exists. It is not a single value, but represents all possible values.

A derivative of a single variable function, at a particular point, can be interpreted as the slope of the function at that point. It is a single value.

Why do you ask? What has caused you to ask this question?