Hi there! They are gorgeous!
How old are there? Do you know? If your older budgie is a couple of years old, or even just close to one year old, then she is a female. Her 'cere' will go a crusty brown when it comes into breeding season..if she was a boy i imagine she would have a dark blue or even a light blue cere by now..shes really pretty, i have a male budgie with the exact same coloring's.
As for the younger one, my guess is that she is a female too....She has a lighty colored cere...
2 snips from the internet...
"Identify a female budgie. A female adult budgie's cere is usually a white or pale brown. As she becomes more fertile and ready to produce eggs, the cere will become a darker tan or brownish pink in color.[5]
If the budgie is fertile and ready to breed, you may also notice the cere thicken and become crusty.[6] The cere build up can be about a centimeter thick.[7]"
"Identify a male budgie. Most male budgies in the breeding mood have a bright or royal blue cere. Sometimes, the vibrant color can appear purple-blue.[2] This color will lighten to a pale whitish blue when the budgie is not in the breeding mood.[3]
If you've identified your budgie as male and notice his cere turn brown, he may have a medical condition.[4]"
As for the name of the colors, refer to this link:
http://puppiesareprozac.com/budgie-parakeet/colors-varieties-mutations-genetics/
Best of luck...
-Mustang