Average so different boys 'and girls' physical development rate slightly. Get an overview of what to expect. Of course there are large individual differences - this is sketched in broad outline.
Gender identity
Children begin to understand that they are either male or female as early as the age of 18 months. Between two and six years of age they begin to identify with others of their gender and have fun and behavior that is gender-typical - so both nature and the environment (cultural considerations), this affects.
Physical growth
Until sometime in middle school is growing in both boys and girls of about the same steady pace. There are no obvious differences until around 10-12 years of age when girls begin to shoot up faster. But within a few years time the boys caught up with them and grow on in height.
Motor development
Boys 'gross motor skills, such as running, jumping and balancing tends to develop a little faster, while girls' fine motor skills, like holding a pen and write evolve faster.
Boys also tend to be more physically aggressive and impulsive. The parts of the brain that controls pleasure emotions activated more in boys at high-risk activities. It does not mean that girls are not active or taking risks - only that boys on average tend to be a little more.
Verbal ability
More boys than girls start speaking late and boys consume an average of more limited vocabulary. Girls tend to be better at reading nonverbal cues as tone of voice and facial expression, which promotes communication skills as they facilitate the interconnection of feelings and words.
This is something you can focus on as you read along with your son. Talk about how the characters in the book feel and how things feel different to different people, so that part of the vocabulary is expanded.
Toilet training
Girls are often pottränade earlier than boys, but it is unclear whether this is due to differences in physical development. It may also depend on who is primarily responsible potty training - it is the mother, it can make it easier to identify with the girls.