-evolution: SyncEvolution for GNOME Evolution
amd64: x86-64 binary (default is 32 bit)
i386: 32 bit x86 binary
rpm: RPM package for SUSE, Red Hat, Fedora, ...
.tar.gz: same binaries as plain archive for other distros

For Debian-based distros an APT repository is available:
http://syncevolution.org/documentation/installation

Before 0.8.1 the evolution-2.6/8/12 suffix determined with which
Evolution the binary was compatible with. As of 0.8.1, the same binary
is compatible with all supported Evolution versions.