In Star Wars, it's all canon unless said otherwise. In Star Trek, it's never canon unless it's on-screen. Star Wars canon is very clearly defined; they have different tiers of it, for goodness' sake.
Really? I've always been told that anything outside the six movies is not canon unless Lucas says otherwise and what is canon in the EU is always subject to change
Do you need a Venn diagram?
The point is the canonicity is not stable with the EU. Heck, even scenes from the movies change in canonicity with Lucas always editing and re-doing them