The phrases different from and different than are both common in British and American English. The British also use the construction different to. Since the 18th century, language critics have singled out different than as incorrect, though it is well attested in the works of reputable writers. If you want to follow traditional guidelines, use from when the comparison is between two persons or things: My book is different from (not than) yours. Different than is more acceptably used, particularly in American usage, where the object of comparison is expressed by a full clause: The campus is different than it was twenty years ago. You can use different from with a clause if the clause starts with a conjunction and so functions as a noun: The campus is different from how it was twenty years ago. 1 Sometimes people interpret a simple noun phrase following different than as elliptical for a clause, which allows for a subtle distinction in meaning between the two constructions. How different this seems from Paris suggests that the object of comparison is the city of Paris itself, whereas How different this seems than Paris suggests that the object of comparison is something like the way things were in Paris or what happened in Paris.