Nice setup. Beautiful budgies! 
I have had them when I was a kid. Very active little birds. Hardy for their size. One pair of mine even escaped after they opened the cage by themselves. Hopefully someone found them and took good care of them.
From my understanding, the green budgie of yours is sexually matured. The blue one is still a juvenile. You can tell that part from the strips on their head. The green budgie is showing a yellow head without any strip, while the blue one has strip all the way down to the nose. When the blue budgie is matured, the head should turn white without any strip. Another sign to see whether or not a budgie is matured is from the eye. You can see the white outline around in matured budgie, while the juvenile will have full black or dark brown eyes without any white part.
It is hard to tell from the photos. Which one is the male, which one is the female?
Keep us updated. 
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