in the online part of calamares , the desktops are installed in Groups. if it was installed in in Meta packages it get also harder to remove some packages if you dont want it.
all things are configured as vanilla. you can make your desktop of your own also.
if you use online installer your system is already up2date do pacman -S xxxx is fine but general, de groups packages in endeavouros is basicly al what you need to run a desktop. calamares is just a installer btw ; if you do pacman -S plasma , it installs all from ‘group’ plasma… groups are basicly different then packages it self, packages self are mostly : package+depency thats needed… but groups are , packages in a group+ depencys what needed.
Recommended NOT change or uncheck them if you do not know exactly what you do
In the end there is no difference as installer is also using pacman to install the packages selected. But installing packages on installed system is not possible with calamares, it is only the initial system installer (also using the tools from archlinux to install needed packages)
You can uncheck packages if you are sure you do not need them inside install procedure but you can also remove them on installed system later…
We do some basic preconfigurations like enable needed services (systemd) and configuring boot process and DM (Login Managers) and some theming is also done from installer…
To be clear, ethtool is useful and I would recommend it but I don’t see it as a required component of a base install. You don’t need it to connect to the network. It is useful for when specific situations come up that require changing adapter settings such as when duplex auto-detection isn’t working.