At the very highest level, the IPv6 address space is divided into six main parts, each having its own purpose and meaning.
::/3 – Special addresses types
2000::/3 – Allocated unicast addresses
4000::/2 – FE00::/9 – Reserved unicast addresses
FE80::/10 – Link-local unicast addresses
FEC0::/10 – Site-local unicast addresses (deprecated, see below)
FF00::/8 – Multicast addresses
The site-local addresses (FEC0::/10) were meant to be the IPv6 equivalent of the IPv4 local ranges 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16, but they were deprecated by RFC 3879 in 2004 because the same address could exist in multiple sites without any way to tell them apart. Their replacement is the Unique Local Address range FC00::/7 (RFC 4193): that’s what you’d compare to the IPv4 private ranges today.