adjective
1
BAD : London is different of Hong Kong.
GOOD : London is different from/to Hong Kong.
BAD : In Argentina, Christmas celebrations are completely different as the ones in England.
GOOD : In Argentina, Christmas celebrations are completely different from/to the ones in England.
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A is different from/to B: 'Alex was different from all the other boys she knew.' Note that most teachers and careful users prefer from .
2
DUBIOUS : My new school is very different than the old one.
GOOD : My new school is very different from/to the old one.
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Different than is used in American English but is rarely used in British English.