How to tell the difference between a boy kitten and a girl kitten?

One way to tell the difference between a boy kitten and a girl kitten is by looking at their genitalia. Male kittens have a small distance between the anus and the genital opening, while female kittens have a larger distance. Another way is to check for the presence of testicles, which are only found in male kittens. It is best to consult a veterinarian for a more accurate determination.