different from, different than

Although both of these phrases are common today, some believe that different than is always incorrect. The reason is easy to understand. The word than follows a comparative adjective or adverb. For example, her car is faster than mine. Or he runs faster than the rest of the team.

But the word different is NOT a comparative adjective. Hence, the use of than is incorrect.

Different from is preferable when two things are being compared to each other.

Your house is different from my house.

The expression different than, however, is acceptable when the distinguished element appears in a clause:

The game of poker is different than it was 20 years ago.

If you used different from and then a clause, you would have to introduce the clause with a subordinating conjunction (usually what) that forces the clause to act as a noun, that is, as the object of the preposition from.

The game of poker is different from what it was 20 years ago.

Example: Cars today are different than they used to be, but his old car is not different from mine.

This problem is thoroughly discussed in the Parts of Speech section on Adjectives. Click here for the beginning of that discussion.