I'm assuming you which to know the difference between ICD-9 and ICD-10 Codes. Well ICD-9 codes were the codes used prior to the implementation of ICD-10 codes. These were generally less complicated, using only a series of digits. ICD-10 codes however were only recently implemented to replace ICD-9 codes. These codes have in addition to digits, a letter preceding the digits. This is organized in a way that allows for easier finding and more specific diagnosis.