Why do hospitals use different procedure codes than physician offices?

The codes are standardized through the industry. The difference you see is probably because the codes designate the procedure that was done. An office visit by a Family Doctor will have a different code than an exam done by an Emergency Room Physician. The capabilities of the person doing the procedure plays into the code as well as what was done. An office visit to a Neurologist pays more than an office visit to a Pediatrician for a cold. These would have different codes even though both are office visits. If the Neurologist medical filer uses the same code as the Pediatrician then he will loose money of his reimbursements.