Before discussing differences, let's reinforce one fundamental idea: boys and girls are equal. What does that mean? It means that boys are not better than girls and girls are not better than boys. Both boys and girls are equally beautiful. We are all equally beautiful. Of course, we are all individuals and personalities. But it's healthy and correct to compare yourself in the past and yourself now, but not yourself to others. That's the best way, especially for your self-esteem.
But boys and girls differ primarily by belonging to the male and female biological sex. A person's biological sex combines anatomical, physiological, biochemical, and genetic characteristics.
To put it simply, boys and girls have different genitals (for example, boys have a penis, girls have a vulva), different sex glands (boys have testes, girls have ovaries), different sex hormones (androgens and estrogens respectively), and a different set of sex chromosomes.
Boys and girls go through puberty differently. For example, girls may start earlier, and boys may start later. Girls' secondary sexual characteristics are, for example, breasts (breast glands) and hips (pelvic shape). Boys, for example, have facial hair (mustache, beard) and Adam's apple.
And also, girls mature and develop faster than boys. This difference is especially noticeable between the ages of 10 and 13.
All these differences are neither bad nor good. It just is. It doesn't make anyone worse or better. Boys and girls can play the same games, like the same colors, the same books. Have the same interest in computer games, fashion and music, and cooking. Anything! Interests, hobbies, music, sports, and other things do not have biological sex. Saying, for example, "It's a boys' thing" or "It's a girls' thing" is wrong.
It's okay to be interested in each other's world, to be friends with boys and girls, to be aware of the specifics of puberty and the development of boys and girls, and to understand and support each other.
But to create, support and spread myths about biological sex or puberty in general in today's world is ignorance.