While that could be true, Blue=Male and Pied=Female, those are babies with purple ceres and you can't sex them with 100% accuracy yet. Going by one being nicer than the other isn't accurate either. I've tried that route. It's still a 50/50 chance and is basically a guessing game. I've "sexed" many purple cered mean babies as female and they turned out to be males. They will also lose those dark bands across their foreheads and get a white eyering as they age.
A light colored bird (the pied) will always have a lighter colored cere as a baby than a dark colored bird (blue one). But they both have purple ceres and all babies have purple ceres regardless of sex. Post a picture of them in two months. By then you should be able to tell the sex. Females will have brown or light, light blue ceres and males will have deep, dark blue ceres.
A male
A female in breeding condition as evidenced by the crusty brown cere. When she's not in breeding condition, her cere is not crusty and can even be a really light blue.
These are pictures from a calendar and a book listed for sale on Amazon.com. I've bred hundreds of parakeets over the years and I don't have one single picture! I've looked & looked but apparently I didn't take any pictures! I don't have any 'keets now at all so I can't run out & take some pictures.
I'm glad they've tamed down. A tame parakeet is a wonderful pet to have. They are so energetic and full of life and are neat, neat birds.