Difference between desktop-install and copying desktop file to applications directory

When we want to add a shortcut to menu. We can do that by creating filename.desktop and copy that file to /usr/share/applications. And there is another way to, that is doing desktop-file-install filename.desktop. What is difference between those two?

Until now, I still use copy method because if I want to remove it, i just delete it. And desktop-file-install seems like doesn't have desktop-file-uninstall.

To quote man desktop-file-install:

desktop-file-install will always try to validate the resulting desktop file. A failure to validate might lead to the abortion of the installation of the desktop files.

In contrast, cp will copy anything.

So there is no desktop-file-uninstall since there is no need to validate files you are deleting.