Why is the portable version smaller than the normal one?

Are there less functions or other limitations?

In http://portableapps.com/support/libreoffice_portable#modifications


We made some modifications to the default version of LibreOffice to make it more USB key friendly (decreasing total install size and the number of writes to the drive, which will increase drive life). These changes are listed here so you’ll know what they are, and so you can recreate the process, if so desired.

Friendly Launcher - LibreOffice Portable Launcher is included allowing you to launch LibreOffice Portable from anywhere you'd like. It automatically handles paths to Java, your documents directory and an included temp directory and set the language automaticly to the actual language of the PortableApps.com Suite. (Manual changes over Tools-Settings will have no effect! But if You will use LibreOffice Portable without the suite it will start with the language You have choosed in the installer and You will be able to change Your Language over Tools-Settings.)
Installed Options - The pieces of LibreOffice included are those that are of use when run portably. Thus, elements like the Explorer extension, ActiveX control etc are left out to save space
Mini Launchers - Launchers for each LibO app are also included.
EXEs and DLLs Compressed - All EXEs and DLLs were recompressed using UPX. This gets our installed size down to one that is a bit more manageable. Additionally, it will speed up use of LibreOffice when you're running over USB 1.1. The options used were: --best --compress-icons=0 --nrv2e --crp-ms=999999 -k
JARs re-compressed - The JAR files in (without the classes folder) have been recompressed at the maximum level using 7-zip, getting our package size down. (For the curious, JAR files are just ZIP files with a different extension)
Additional Icons: By default, LibreOffice Portable includes the Galaxy icon set. Add other icon sets by installing the LibreOffice Portable 3.x Image Pack.
The portable version comes with its own MSVCRT runtime in order to work on systems without local installed runtime too