Distinguishing parrots by color, size and shape will not work, the colors may be different, and the sizes too. The main difference between birds is wax, by which parrots should be distinguished by gender. You can also find out the approximate age of the bird. When matching colors, pay attention to the area on the beak, on which there is no feathering, this is the wax.
Females change their color more times than males. When they are first born, it has a light shade. At about 4 months, females can boast of a beautiful blue waxworm, but by 6 months it begins to fade and brighten altogether. Then the color of the unfeathered part changes to brown and remains that way for life.
In male chicks, the wax is bright and beautiful, the color is lilac. Gradually, it changes to blue, and it remains unchanged. It is precisely by the blue wax that you can distinguish the male from the female. But be careful, if you have birds of different ages, you can confuse them, because the female budgies also have a blue color for a short period of time.