Generally on short Haul there are 2 types of Premium Cabins

"True" Business Class (Called First Class on most US Airlines)

This is where there is actually a dedicated premium cabin such as Air Canada, American, Continental etc

"Convertible" Business Class

This is on most European Airlines. The move the divider and the seats change between J & Y depending on demand. The middle seat is made smaller and the aisle and window seats bigger to create a 2x3 or 2x2 configuration (depending on the airlines) with a slightly wider seat