There is a difference between printer toner cartridges and a drum unit; although both of them play a vital role in laser printing. New users are commonly confused about the uses of these two consumables and have difficulty distinguishing them.
The printer toner cartridges hold the toner. It is responsible for creating the images on printed materials. A toner cartridge may come in high yield, standard or extra high yield. Color laser printers also typically carry 4 colors – cyan, magenta, yellow and black toners (CMYK).
While the cartridge holds the toner, the drum unit acts as the carbon paper. It transfers the toner to the printing material. The drum corresponds to a certain toner color only. Therefore, if you are using a color laser printer, then you will also have 4 drum units to replace. On the bright side, drum units have high capacity which normally reaches up to 20,000 pages. There’s a significant gap in between replacement.
While toner cartridges can be refilled when empty, drum unit needs to be replaced since it only wear out and deteriorates when it reached its maximum capacity. Some toner cartridges however are integrated with drum unit.