Lots of people say that something is different than something else, but the grammar police would write you up and ticket you, preferring the expression “different from.”
The AP Stylebook succinctly says “Different takes the preposition from, not than.”
Example: That version of the specification is different from the one we are using.
Two things are being compared, and one differs from another. Make sure that both sides of the sentence have a parallel construction.
Example: The pumps used in the north part of the field differ from the pumps used in the south part of the field.
Webster, however, says that “different from” has been used since the 17th century by many of the best-known names in English literature.
“Different than” can be used when followed by an elliptical clause (one with some words left out of the parallel construction).
Example: The actual process is different than the schematic.
Parallel construction of this sentence would use “different from.”
The actual process is different from the process shown in the schematic.
To differ from something means to be unlike it.
To differ with somebody means to disagree with them.
Apparently, various style books differ with each other on the topic of “different than.”
When in doubt, use “different from,” as it is preferred by most grammarians and the SPE Style Guide.