First, what is the same between the genders?
Psychologically, we all are impatient and want results yesterday. We all want instant abs, 10 minute workouts, diets where they can eat all they want, and want a magic fat loss pill.
Also, on the cellular level and for the most part an anatomical level males and females are pretty much the same. Muscles and bone tissues are the same no matter what gender. Whether guy or gal, if you train well you will develop a fit body while if you train poorly, you will be left with little to no progress.
So how are the genders different?
Where males and females differentiate the most is hormones, specifically Testosterone and Estrogen levels. A healthy male can produce as much as 20 times the amount of testosterone than his female counterpart in a day. Testosterone plays a key role in building muscles and repairing damaged tissues. This also means that females have a hard time building up massive amounts of bodybuilder-type muscles. Hormones also play a key role in fat deposit sites so females tend to hold more fat deposits in the hips and thighs.
Anatomically, while men and women are similar there is some key differences in the hip and knee structures. The hip and knee issues can originate in the pelvis/hip structure. According to the authors of Women’s Health and Fitness Guide (2006), the female pelvis has a number of differences as compared to the male pelvis for the purpose of accommodating childbirth. The differences can predispose female athletes towards the femur being tilted inward compared to a male. This increased angle of the femur as compared to the vertical placement of the tibia that can be a source of injury.
Generally, as a trainer I run into men have an easier time training upper body while women prefer lower body. This is typically because of Societal Standards of Beauty… men focus on manual labor and don't worry about having calloused hands. Women tend to shy away from upper body exercises out of fear of "getting too big and manly" and tend to focus on lower body thinking they will get that "toned" look everyone wants. The psychological aspects of each gender brought on by societal norms and ideas of beauty has a profound affect on how most people train.
Also, it should be noted that from a Personal Trainer's perspective, many women are hard to deal with 1 week out of every month… men on the other hand are always a pain to deal with. (This is a joke... don't spam me with hate mail!)
So what should you take from this?
No matter your gender you should give 100% if you want good results. Your workout and nutrition plans should reflect your individual needs and limitations, but aside from some hormone balance and the knee issues the gender lines have little to do with training your muscles.