Different From or Different Than?

You can’t go wrong with different from. That’s the standard rule. Different than is used frequently and is becoming more accepted in American usage. (Different to is accepted in Britain, but you rarely hear that in America.)

I want something different from that.
My definition is different from yours.
That’s different from what it was supposed to be.

Different than is more accepted before a clause (a complete sentence) and is interchangeable with other than.

It turned out to be different than I had imagined.
He is a different person than he used to be.

Trick to Remember:
Different from is always accepted. Different and from share the letter f.

However, you can still use different than in most cases, though I’d be wary of English teachers.