Neons, False Neons and Cardinals are different species of fish. Each has it's own requirements, but all 3 have several things in common. They are blackwater fish from deep continental South America.
They require soft acidic water but the more commonly available Neon and Cardinal are more resiliant to harder water.
The commonality is that NONE of these species tolerate pollution well, thus newly established tanks or uncycled tanks are totally inappropriate for them. Most people would not recommend adding any of these species to a tank that has not been established and stable for at least 3 months, more 6 months.