Could someone please explain to me how consumer mesh networking systems are technically different than using extenders/repeaters?

I've been searching and asking around about this for a while now. Every article or explanation I can find basically stops at saying "mesh networks work together to blanket your home with wifi."

I'd like the next level of detail. In my house I have a main router and I have an extender (not repeater) setup using ethernet for backhaul to the main. The extender is presenting the same SSID/password, and DHCP is disabled (set to forward to the main), which is how I've heard it described to get a "seamless" setup.

However, in reality it's not seamless for me. If I have a device close to the extender, then walk to the other side of the house close to the main, I usually stay connected to the extender until the wifi gets cycled on/off (manually, or device goes to sleep, etc).

I assume/hope that mesh networking solves that problem, but I'd like some confirmation and technical details. I assume I'd have the mesh nodes all using wired backhaul, so this is just about the "stickiness" of clients.

Does the mesh system automatically/seamlessly bump clients between nodes depending on strength? How do they do that? Isn't choice of AP a client-side decision?

The root of my question comes down to trying to figure out if I should move to a mesh system, or if there's some way I can improve my router+extender to solve my problem.

Thanks for any help.