The Budgie in the first photo is between 6 months and a year old; the Budgie in the second photo is most-likely at least a year old or older...You can tell by the black-lines on their heads, or lack there of, going down their forehead; the closer the black lines are their cere, the younger they are, the more white they have on their foreheads, the older they are...Generally when the black lines are about half-way down the forehead, like the Budgie in the first photo, that puts them at at-least 6 months old, and with this one they have already started receding back away from the middle of the forehead, that's why I'm saying at least 6 months old but not a year...With the second Budgie, it's entire forehead is white, and the black lines have receded beyond the forehead, so it's at least a year old, but based on it's eyes I don't think it's much older than a year, maybe a year and a half...
****Incidentally, as far as sexing them goes, the Budgie in the first photo is too young to sex, as right now I'd call it a female, but if it's cere turns completely pink in roughly the next 6 months, then it's a male, if it stays tan/cream colored after 6 months or so, then it's a female. The Budgie in the second photo is definitely old enough to sex, however the lighting in that photo makes it hard to tell if it's cere is pink or tan/cream colored, if it's pink then it's a male, if it's tan/cream colored then it's a female...