What is difference between CAPsMAN and Mesh? CAPsMAN is for managing multiple APs and Mesh is for creating WiFi that's "surrounding" whole (fe.) home through multiple APs with same SSID?

Capsman is for centralized ap management. Each ap still needs a wired connection to the network.

Mesh is a term which generally means that the APs connect to one another and the network via one of the wireless channels instead of a wired Ethernet cable.

The mesh term is often confused when you use multiple APs in a network when using the same SSID.

You can have APs using the same SSID on your network (via capsman or manually configured) and not be mesh.