Notepad++ Installer: Take this one if you have no idea which one you should take.
Notepad++ zip package: Don't want to use installer? Check this one (zip format).
Notepad++ 7z package: Don't want to use installer? 7z format.
Notepad++ minimalist package: No theme, no plugin, no updater, quick download and play directly. 7z format.
SHA-1 digests for binary packages: Check it if you're paranoid.
Notepad++ source code: The source code of current version.