Our A340's have the following configuration, 6P 42J 204Y while our 777 are equipped with 12P 26J and 202Y.
The A340 is used on long-haul thin routes that doesn't require the high-yeld capacity that the 777 has. The 777's are used on strong high-yeld routes such as SIN, GRU, LAX, LAD, EZE or JFK.
hope it helps,
AF Cabin Crew.
Click for large version
Photo © Alain Mengus