First let’s talk about these Brother toner cartridges. These are the ones responsible to hold the toner particles which are used to create figures and images. So basically it works as a tank or a container. A monochrome laser printer only needs one cartridge particularly the black. While a colored printer on the other hand requires three to four colors such as black, cyan, magenta and yellow. There are some colored types that can use more than four cartridges aside from the general CYMK. Hence there are these light cyan, light magenta and light yellow colors.
The imaging drum or also referred to as drum unit, is the component that transfers the created image through the toners onto the paper material. Inside the drum unit there’s a photosensitive drum that holds the formed image (text, lines, photos, etc). This is then pressed and rolled into the sheet to transfer the image through heat and pressure, and after that you now have your printed material.
One common mistake that some users commit is replacing the drum along with the cartridge that goes out of toner. In case the machine prompts you with an error message to replace the drum, that’s the only time you will need to install a new replacement, otherwise don’t remove it inside the printer. Toner cartridges can be replaced once they’re emptied, damaged or faulty. But it is not necessary to re-install a new drum unit unless it is also under the same condition.
Since they are two separate components, you shouldn’t be confused. Here’s a hint, the toner cartridge is the one you slide into the imaging drum, not vice versa. For a colored printer, there should be four drum units for each toner color. The typical arrangement is something like this, the black goes at the front, next is yellow, followed by magenta and cyan at the opposite end.
Remember that you only need to replace the consumable that goes empty or is damaged. Unless both the cartridge and drum became obsolete and the warning from the status LCD indicates that those two should be replaced.
I certainly hope you now have a better idea on what’s the difference between a laser toner cartridge and an imaging drum unit.