How Can I Identify Apps Installed by My Desktop Environment vs. My Distro?

It sounds like you're asking about the applications bundled with different DEs versus what's included in the distribution itself. Most Linux distributions use a package manager, and the applications are typically installed using that. You can usually see what came with your DE by checking the meta-packages. For example, installing KDE might include apps like Konsole, whereas GNOME will include its own terminal application. If you have both installed, you'll notice both terminal options in your system.

Definitely! Each DE has its own set of default applications, often bundled within a meta-package. So when you install a DE like KDE, you might get packages like plasma-desktop for the basics, but if you want all the bells and whistles, you'd go for something like plasma-full, which adds more KDE-specific apps. Just keep in mind that different distros might have variations in what is included.