What is the difference between IPS Empress Esthetic vs IPS Empress eMax?

Both of these pressable ceramics are made by Ivoclar with Empress being and older product. eMax is a newer and stronger porcelain that can also be used for both front and back teeth.
Most highly esthetic porcelain is made by hand and not machine. I prefer eMax that is hand layered over one that is stained. Many dentist are using milling machines to make eMax veneers and crowns, and I would strongly avoid getting these restorations as they rarely look as nice as ones that are hand made.