It is different from, never different than.
The word than is always used in a comparison: e.g., farther than, better than, less than,
more intricate than, older than. There will always be an "er" or the word "more" or "less"
with the word than. Since there is no way to get a comparison word in the sentence with
different, it can never be different than. It has to be different from.
...The book was different from what I had expected.
...Mine is different from his.
...The cake was different from what I remember.
Happy punctuating!
Margie