There are a few key differences between the Rancilio Silvia V5 and V6 espresso machines. The V5 is a semi-automatic machine, while the V6 is a fully automatic machine. The V5 has a single boiler, while the V6 has a double boiler. The V5 has a copper heating element, while the V6 has a stainless steel heating element. Finally, the V5 has a fixed steam wand, while the V6 has a 360-degree swivel steam wand. These differences make the V6 a more advanced machine than the V5, but both are excellent espresso makers.