Should one use the PPA or manually install the .debs from http://www.libreoffice.org?
Is there any difference between the two? How long does it take for the ppa to upgrade to the latest version?
PPAs provide a new source of software for Ubuntu.
They are updated to the newest version seen as stable with your system. They will list updates much like normal ones in the Update Manager (unlike .Debs), and the admin of the PPA should not list the most recent version to sent to older systems if it is incompatible.
.Debs provide none of these protections.
Because of that, and that the installation of LibreOffice with .Deb packages requires the download and extraction of several .Tar.gz archives and subsequent installations, I would recommend using the PPA, in the Terminal if possible (far faster).
Unfortunately, the PPA is only for currently supported versions of Ubuntu.
To add the PPA, update the Software Sources, and update/install just libreoffice, execute:
sudo add-apt-repository ppa:libreoffice/ppa
sudo apt-get update && sudo apt-get upgrade
sudo apt-get install libreoffice
If you want to continue using the latest version tested (stable) for you, just run the Update Manager, check for updates, and install them regularly.
