The 378 range adds light cyan and light magenta to the usual black, cyan, magenta and yellow. These printers are built for photo output, and the two extra inks give smoother tones in skies, skin and other gradual shades. All six need to be fitted for the printer to operate.

They fit exactly the same printers — the XL simply holds more ink. If you print often, 378XL works out cheaper per page and means fewer cartridge changes. For light use the standard 378 may be enough. You can run one of each in the same printer without any problem.

Yes, for everyday photo printing, greetings cards and craft work. Results depend heavily on the paper — a proper coated or glossy photo paper makes far more difference to the finished print than the cartridge brand. For exhibition or archival work, most people stay with genuine Epson.

Yes. The 378XL range uses separate cartridges for each colour, so you only replace the one that has actually run out. A multipack normally works out cheaper than buying four singles, so it's worth a full set if you print regularly in colour.