The Enhanced seat data is what we pull directly from the SSIM. The SSIM is what the carrier provides to Cirium, and there is an optional field that contains the Seat-by-Cabin information on a per-flight basis. If a carrier provides that optional info (called the Aircraft Configuration/Version (ACV) field), then we pass that into the tool and it is displayed when the user has "enhanced seats" selected in their user>account settings.
The Traditional seats are values we Diio have curated over the years, and it is a combination of some default seat counts and specific client over-ride seat counts, at a monthly level. In other words, the same traditional seat count will be shown for all flights on a given equipment for a specific carrier during a given month.
Traditional seat counts are occasionally adjusted for a specific carrier to more closely align with their Enhanced/SSIM submitted counts. Users should consider this when they compare reports they ran in the past with a fresh copy run today, as seats and ASM/ASK values might have changed.
The easiest way to see the difference in these options is to run the Reference>Equipment/Seat report. Try querying airline Air China, CA. You will see each equipment listed several times. This indicates that they fly the same equipment in different configurations, so the Enhanced seats will show the different counts for each layout, while the Traditional will show a standardized value for the same codes.
The user can select which seat count option they prefer via the User>Account settings page.