luaotfload (the package doing OpenType layout under the hood for LuaLaTeX) has two font processing modes;
base mode which tries to made as much of OpenType lookups to traditional TeX ligaturing and kerning mechanisms (think of it like creating TFM files from OpenType fonts on the fly) and it is limited by what TeX can traditionally support, and
node mode which tries to do faithful OpenType processing entirely in Lua.
Renderer=Basic maps to the former, and
Renderer=Full maps to the later.
Renderer=Basic is needed for
Ligatures=TeX to work with some fonts, is an artefact of how this feature is implemented in
luaotfload, it is a bug actually, but the development of
luaotfload is stalled…