Whats the difference between PG-30/CL-31 and PG-40/CL-40 Canon ink cartridges? -

PG and CL are black (PG) and color (CL) codes and the set will either be for different printers or one will be high yield (more ink) versions of the same cartridges and the other standard. My Canon takes 37 and 38 standard and a 40 and 41 high yield. Only cartridges that are designed to work in a specific model printer will work. If another number cartridge is used the printer will not work. Edit No difference in ink quality as the ink is the same ink just more in them. I think its about 4ml extra for colour and about 5 ml for black. I seem to remember seeing something comparing sheets with high yield and standard and it saying something like 80 sheet extra out of the high yeild. Untill you buy the two to compare against your own usage you will not be any the wiser, but it looks roughly like a third extra ink.