The desktop environment is all the stuff like the taskbar, the settings menus, the application launcher, the login screen, that kind of thing. It’s the system level user interface.

You choose which one by which distro you download. Linux mint uses cinnamon, Ubuntu and fedora use gnome. There are “flavors” of Ubuntu and fedora that use KDE. That’s why I suggested ventoy: you can download a few different ones and boot into them without making a new thumb drive.

If you don’t feel like bothering with any of that, just use Linux mint. It’s good.

• before you switch, sort out your apps. Look at what you use on windows, see if it runs on Linux. If not, find a replacement that does and test it out.
• Most Linux distros can boot into a desktop from a thumb drive. You can play and test without touching your windows installation.
• in that vein, ventoy is neat. You can make a bootable drive and drop ISOs in a folder to boot from. No messing with etcher or whatever it’s called
• desktop environment matters as much as the distro. Check out gnome, KDE, and cinnamon.