@MattDavis,
I feel like I keep saying the same thing over and over again because you and Thomas keep ignoring my key point.
The difference is objectively testable. I don't consider much of what is considered social science in the same category as "hard" science. However there are claims from social sciences that are objectively testable, and such claims are scientific by my definition.
A claim about morality such as "Americans don't accept cannibalism" is objectively testable. You can set up a a survey or observe Americans behavior. Anyone objective observer from any culture doing such a study would reach the same conclusion, that Americans don't accept cannibalism (point out the rare outliers that are met with disgust by everyone you are just being difficult).
A claim such as "cannibalism is wrong" is not objectively testable. There is no objective test you can even propose to determine whether cannibalism is wrong or not.
That is the reason I reject the idea that any absolute morality is valid. It is not objectively testable meaning that anyone who has an opinion is just as correct as anyone else.