What is the difference between categorical and hypothetical imperatives?

What is the difference between categorical and hypothetical imperatives?.

The Categorical Imperative and Moral Action

Consider the Categorical Imperative that Kant formulates in the reading from his work “Groundwork for the Metaphysics of Morals”:

“I ought not act, less I should can will my maxim to become universal law.”

What is the difference between categorical and hypothetical imperatives? Is it or is it not the case that the Categorical Imperative (we should only act in such and such a way, that in every such instance we could act that way) provide appropriate direction for a course of moral action? Consider specifically the response to the objection to Kant’s position of the Inquiring Murderer.

Required Reading: Immanuel Kant “Groundwork for the Metaphysics of Morals”

Recommended Reading: “Kant’s Moral Philosophy”, Introduction, Sections 1, 2, 3, & 4 <  http://plato.stanford.edu/entries/kant-moral/index.html#toc (Links to an external site.)Links to an external site. >

What is the difference between categorical and hypothetical imperatives?