Most babies born with birth defects are male. If a female has a defect, she still has another copy of that X chromosome.

Veins in males tend to be larger

Males are 4 times more likely to be autistic than females.

Females tend to have more vertical foreheads, while males' foreheads tend to be sloped.

In males, fat gets deposited between organs. In females, it forms a ring around the abdomen. This is why you can typically tell someone's sex from an MRI, and why liposuction is easier in females.

Perhaps unexpectedly, males have longer eyelashes on average.

The first finger of a female's hand is usually longer than the third. With males, it's usually the other way.

Only females can pass mitochondrial diseases on to their offspring.

Males are 3 to 10 times more likely to stutter.

Although both sexes lose hearing on either end of the spectrum, males tend to lose more hearing of high pitched sounds, while females tend to lose more hearing of low pitched sounds. People have noted that as time goes on, males and females literally lose the ability to hear each other (it's a joke).

Females are significantly better at distinguishing between shades of various colors than males.

Blood flow is more evenly distributed in the male body. In females it is concentrated around core organs and the pelvic region.

There are about 1,000 genes that vary between males and females with regards to the liver. This is why the sexes process everything from alcohol to Tylenol at different rates.

Females tend to have a broader face than males

The external occipital protuberance (the bump on the back of your skull) is bigger in males than in females.

The male jaw bone is heavier than the female jaw bone.

Some studies have found men to have more standard deviation in IQ. This has been spun by the media to partially account for why both more mentally handicapped individuals as well as geniuses tend to be male. (note: the media tends to draw more conclusions from inconclusive studies than scientists do.)

Women tend to gather a greater proportion of their energy from aerobic respiration; men tend to spend more time in anaerobic respiration, relatively speaking.

The top edge of the eye socket is much sharper in females than in males.

Females have better peripheral vision than males, while males are typically better at scanning. This is thought to have evolutionary origins (hunters vs gatherers).

During heart attacks, males experience the "classic" symptoms like chest and jaw pain, while for females the symptoms can be quite diverse. In fact, it can often be confused for heart burn.

Females' blood contains more water and about 20% less red cells.

Although female brains are better at many other tasks, male brains are geared towards giving them better spacial cognition.

Females tend to get motion sickness more easily, especially if they are pregnant.

Males die more from almost every disease except breast cancer, female reproduction disorders, and benign tumors.