They're not a different morph - they are a line of pastel and if they are produced from a pure lemon, tend to be brighter than other lines.
As hatchlings, lemons are pretty UN-impressive - and in fact, Kevin at NERD (the originator of this line) has stated that he generally doesn't photograph them until after their fifth shed, when they start to show their true potential.
When you're shopping for any pastel - keep in mind that orange turns brown as adults - so you want to try to find a baby with great head blushing and the least amount of orange on them as you can find.