The recently released 2021 24-inch Apple iMac all-in-one desktop computer with M1 SoC comes in three variants, with the differences mostly listed on Apple's website. However, cooling system differences between the base iMac 24 and mid-tier iMac 24 have seemingly been omitted, even though they could affect the performance of the M1 Apple Silicon.
https://www.notebookcheck.net/Not-all-M1-iMacs-are-built-the-same-Potential-buyers-of-the-2021-Apple-iMac-24-should-be-aware-of-the-cooling-system-differences-that-could-affect-performance.541335.0.html
Given the excellent thermals of the M1 this will have minimal impact.
If that was the case why not only place 1 fan in all the SKUs?