On W32, the shell can do the right thing with every file, because extensions are registered with the explorer. See MsShellExecute.
When a file is ‘right-clicked’ from explorer, some of the available actions are ‘verbs’. The default verb is displayed in Bold face (in the right-click menu), and will be executed by default (from a double-click). WThirtyTwoShellExecute exposes all of these verbs to the emacs user whether visiting the file, or while in Dired.
On Unix systems, the shell usually cannot do that. On Unix systems therefore, we must use something like TrivialMode, OpenWith or RunAssoc instead.
If you use Dired+ with w32-browser.el you can take advantage of MS Windows file associations in Dired. Just use ‘C-RET’ to “open” a file using its file-association Open operation. Use ‘M-RET’ to open Windows Explorer to that file or folder.