It can sort of depend on the distro, there are a lot of Debian-based ones such as Debian (obviously), Kali, Ubuntu, and then ones based on Ubuntu like Mint and Pop!OS, those all largely work the same under the hood, ie you’d use .deb files and something like sudo apt-get install to install something.
Then there are Arch-based ones like Arch and Manjaro, which are a bit more different, you’d use pacman or yay or paru to install things instead, and they have things like the AUR, which is a big user-maintained repository or software that has just about everything on it.
Then you have the Fedora based ones and SUSE based ones, which are different again in other ways. And some more unique and weirder ones like NixOS which is having a bit of a moment, whereby you sort of configure the entire system in one single config file and rebuild it each time (as I understand it, that might be a bit off 'cause I’m still learning.)
So yeah it sort of depends. And then you have desktop environments like GNOME and KDE which aren’t distros, but do affect how the whole system looks (and functions, to an extent.) And these are largely agnostic of the underlying distro, so you could have say a machine running Debian with GNOME next to a machine running NixOS with GNOME which would look very similar from the desktop but would be hugely different under the hood, and two machines running Arch, one with GNOME and one with KDE which would look totally different but be functionally the same.