From my own observations and practices, the main body-language difference is the body language of dominance versus passivity. Learn that, and you're golden.
The basic premise is that men tend to use dominating and standoffish body language. They take up a lot of space when they walk and when they sit. Legs wide, arms wide, and they use more powerful body language that basically says "I am in control of this space." And they tend to not stand or gesture too close to others. They can be very defensive and closed-off with other people, in a "don't get too close to me" kind of way, with body language that's like "I'm in control of my space, you're in control of your space, let's keep it that way."
This may just be my own personal observation too, but self-confidence is a more masculine thing. Whenever I listen to guys talk, all I hear is "yeah, I did this and this and this, I'm pretty awesome."

They sound more like they're bragging when they talk.
Women use more passive and welcoming body language... while male body language is very outward, women's is more inward... crossed legs, arms in closer to the body, and much less of the dominating "establishing a personal bubble that you better not cross" behavior. Slower, more fluid hand motions and gestures are more feminine, as well as gestures that, in a way, reach out to the other person as if to include them in your conversation. (Watch a woman speaking in front of an audience and you'll quickly see what I'm talking about,) while blunt powerful gestures are more masculine.
Also, when women talk, it's kind of girl-code to play down your own accomplishments, and preface things with "I don't know if it's any good, but..." and other things that, rather than directly having pride in something, leave space open for the differing opinions of others just in case they disagree with you. Saying "yeah, I did pretty good" is a more male thing, where "I think I did a decent job" is more feminine, because you've added in the "I think." Women speak more as if things are completely just their own opinions, their own interpretation, rather than making generalizing confident statements that directly or indirectly imply "I know I'm right."
I'm just scratching the surface here, but that's the main one, is the dominating behavior versus passive behavior. Taking up space and expecting others to get out of your way, versus taking up as little space as possible and hoping that you're not offending anyone else.