Yeah the DE is your desktop, launcher, window manager, setting manager etc. So Gnome, KDE Plasma, mutter, etc. It is what most people will notice.

The distro is basically a package manager and assembly of packages. So if you were to use ubuntu for instance, there is a default DE, but you'll notice there are a bunch of "flavors" available. These are mostly different desktop environments and default applications, but all of the stuff in any of them are in the package lists and available to install regardless of flavor.

The main differences between distros are

• release cadence
  • fixed. They release a major update on a regular schedule and only backport bug fixes and security patches
  • rolling. One package set that every installation always updates to latest
• package management
  • some are able to manage packages purely by GUI and some you must use the command line (or if you can use GUI at some point you might have to fall back because it doesn't have first class support)