Ink tank vs cartridge

[Tithis]

I'm looking to buy a printer now that I'm in college and will be needing it more. Since I've always wanted a scanner I've been looking at Canon MFC's and think I'll be going with the Pixma MP210 or MP470(if its still on sale on newegg)

They both include cartridges with them, however I wanted to see what replacements would cost in the future. I looked on Canons website and noticed that they list both ink cartridges and ink tanks. The tanks are about 5$ more each. What is the difference between an ink cartridge and an ink tank? Does they tank store more ink, or are meant to be refilled?

[ski]

"The individual ink tank system is extremely economical since there is no need to replace the entire ink cartridge when just one particular ink runs out. In addition to ink cost reduction, the capacity of each ink tank can be also increased, resulting in significant savings in the long run. Moreover, transparent ink tanks provide visible confirmation of remaining ink level and the ink-level detection system automatically monitors all color ink levels and communicates with the computer, allowing the user to check which colors are running low in real-time."