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 10.04 through 11.04, with 12.04 testing, so if you're running 11.10, the PPA is useless.
It also looks like 10.04 to 11.04 haven't been updated to 3.5, this may be because it is incompatible, or because it has simply not been tested.
To add the PPA, update the Software Sources, and update/install just libreoffice, execute:
If you want the global menu, install
If you are running 11.10, or just enjoy wasting time and/or bandwidth, you can download the .Debs (the are three) for x86 (32-bit) or x86_64 (64-bit) systems, then just select your language, the version you want (3.5 recommended), download, extract, install.
Extraction and Installation should be pretty simple, just double-click on the .Tar.gz files and use the Archive Manager to extract them, then install either by opening the resulting .Debs in Ubuntu Software Centre (must be installed in the order listed) or with GDebi or in the Terminal.
Note that LibreOffice 3.5 is available on the site is not available in the repositories or PPA because it has not been tested with versions before 12.04.
If you want the latest version tested (stable) for you, just run the Update Manager, check for updates, and install all.
Running software on systems that have not been tested for compatibility (such as LibreOffice 3.5 on Ubuntu 11.10) may lead to stability and security issues.
there are no difference man you can use anyone only different that software download and install from something like ubuntu software center and repository are purport and easier for beginner user like to download and install without face any problem me and other thing no difference
and about libre office man you can you download it from main site (download deb files because you use debian Distribution) and after that use this command with it sudo tar -xvf (name of download files) if it comperessd with tar.gz
or use directly sudo dpkg -i (name of download files) if it download with deb extenison sorry i didn't download it before so i don't know any of that will be downloaded
or best thing to download and install it automatic from ubuntu software center and write in search libreoffice and choose libreoffice writer and press more info and choose all add-ons and then install
you can follow this link to install libreoffice from terminal if you want that
latest verison for libreoffice yet is 3.5.0 from main site
Have a look here