Making Sense of it All

Ok what is the difference between hemp and marijuana. I know one gets you high and one doesn't. I know both are cannabis sativas and I have seen pics of both and they are exactly the same. So how does one get hemp and not marijuana? I am really confused and have been lookin around on the net for over an hour and havent found a damn thing.

Hemp is a male plant that only produces pollen sacs and a female plant produces marijuana

I'm sorry to say that from what I have read on government websites that is incorrect. The hemp plant also produces buds (flowers) but the thc content is far too low to get anyone high (which is why it's legal). I'm still trying to make sense of it all.