First of all, our OP asks one question in his thread title and another slightly different one in the body of the post.
So knowing a little about refilling Canon printers lets me first clarify the differences.
(1) The first question to ask in refilling is what brand of ink jet are you filling, and even then its not always that simple, as even within a brand, different inkjet technologies might be used requiring different inks correct for that type printer branded printer.
(2) Once you know your inkjet printer, a refill ink must match OEM specifications in viscosity, pigmentation, color match, and a wide variety of other specifications. So using a ink blended for a HP in a Canon is going to be a certain disaster and vice versa.
(3) Then one must make a ink subtle distinction, because typical inkjets vend ink in the form of cartridges. Once the OEM cartridge you buy is depleted and becomes empty, one can merely refill the empty cartridge with a new ink, and keep on printing. Or you can buy another new OEM cartridges. Or you can buy a third party cartridges that has a brand new cartridges full of 3'rd party ink and save at least 50%.
But wait, in the last decade or so almost all ink jet printers makers, threw in another joker into the deck, by adding chips. Meaning in short, unless you can find a work around, you can refill your depleted cartridge, or buy a cheaper third party cartridge, but when you try to use them in your fairly new inkjet, your chip will tell the printer your new or used cartridges has no ink and the printer will refuse to use it.
For a better discussion of ways to get around chips I can only refer you to the website I learned to refill. And it also helps to be butt lucky and be able to be one of the last to buy a non chipped Canon. I am still refilling my ip4000 dirt cheap, as I can print in full color for cheaper than my MFC laser can print B/W.
http://www.nifty-stuff.com/forum/