Hey Nancy, I think it's mostly the value range. If I squint at the image I can't really tell what's supposed to be in the foreground and what's supposed to be further back.
waterfall piece is cooooool
Hey Nancy.. I like the water fall one. First one needs more clarity in terms of the shapes. Kepp working on the waterfall one by pushing depth more. if the light source is right behind the water fall, overall value should be little darker and show clear separation between light plane and shadow plane. Also add more red to your green color on the trees.