Is there any difference between 树 (shù) and 木 (mù), in the meaning of "tree", or they are interchangeable?
树 more often means tree in modern language, while 木 usually means wood, as in 木板 (plank) or 木材 (timber).
An olive tree is 橄榄树, while a birch is 桦木. Most trees are 树, though.
树 = tree, 木 = wood or wooden. Pretty much the same usage as in English