We all have our pet grammar peeves, usages that, when we hear them, affect us like the sound of a fingernail against a chalkboard.
I’ll bet I’m not the only one who shudders to hear sentences like these:
A boxer is different than a Doberman.
This car is different to that one.
Yet, are these usages really incorrect?
According to the entry for different from, different to, different than at Bartleby.com,
These three have been usage items for many years. All are Standard and have long been so (different to is limited to British English, however), but only different from seems never to meet objections.
Elements of Style weighs in against different than:
Here logic supports established usage: one thing differs from another, hence, different from. Or, other than, unlike.
From H.W. Fowler comes this pronouncement:
That different can only be followed by from and not by to is a superstition.
He points out that “writers of all ages” have used different to. He does not mention the use of different than.
It would seem, then, that any of the three is acceptable.
Nevertheless, the concluding advice at Bartleby.com agrees with my own:
…for Formal and Oratorical levels: stick with different from.