OEM Cartridge:  An OEM Cartridge is one made by the Original Equipment Manufacturer. If you own a Brother printer for instance, then the Brother brand is the OEM cartridge for your printer.

Compatible Cartridge: A compatible toner cartridge is made by a third party manufacturer and is made up of all new compatible parts. It has a similar quality to an OEM cartridge.

Remanufactured Cartridge: A remanufactured cartridge is when a manufacturer takes an original OEM cartridge, disassembles it, tests and replaces any worn parts, fills it with toner and re-assembles.