Still, just because you don’t see much of the changes visually doesn’t mean there’s no change under the hood.
In the past 5 or so years there have been some pretty major changes in the way macOS works "under the hood." Especially when it comes to the boot process, security, APFS and the way the kernel, user space and extensions all interact.
There are no such major changes with Tahoe, evidenced by the fact that most hackintoshes running sequoia can run Tahoe with minimal changes
Tahoe is for the most part Sequoia with a new UI