What is the difference between jumbo neon tetra and cardinal tetra?

Besides their patterns. On petsmart's site, the jumbo fish are said to only get to 2'' and the cardinal to 3''. And supposedly, the black neon tetra are the same as the jumbo neon? Do the neon really get that big, or smaller? And do neon and regular ones mix? Like in a group of 4 (2 and 2)?