They are the same metal spelled two ways: aluminum is standard in the US, Canada and the Philippines, while aluminium is the spelling used almost everywhere else, including the UK. Remember it by the extra "i": aluminium keeps the "-ium" pattern of other elements like sodium and calcium.
The core difference
Aluminum and aluminium are regional spellings of the same element, not two different things.
- aluminum — the American, Canadian and Philippine spelling: The pan is made of aluminum for even heating.
- aluminium — the spelling used across Britain and most other English-speaking countries: The drink cans are made from recycled aluminium.
How to tell them apart
Both spellings trace back to the same 1812 coinage by the chemist Humphry Davy, who first used the form "alumium" before it settled into two rival spellings. The "-ium" version was chosen to match other element names such as sodium and potassium, which is why it caught on outside North America.
The mix-up usually shows up in product packaging and recipes: a US site will list "aluminum foil", while a UK supermarket sells "aluminium foil" for the identical product. Neither spelling is a typo; picking the right one is simply a matter of which English you are writing.
