You can obtain KVIrc in three ways:
The official packages are released least frequently but are the most stable ones. Each official source package is well tested and will probably compile on your system. You also have more possibilities to find a binary package suitable for your system. The on-line FAQs and documentation refer to this type of package.
The development snapshots are unofficial packages extracted from the SVN on a non-regular basis. Each snapshot reflects the SVN state on a particular revision and you're likely to find a really recent one. The packages have been tested on at least a couple of systems and have a good possibility to compile on yours. There are also some binary builds available.
The latest bleeding-edge sources can be downloaded by using the SVN system. We're trying to keep the SVN as "clean" as possible but finally the sources are not guaranteed to compile. The SVN method provides only sources: there are no binaries.