The Long version adds seasons that last about 1.5 days in Minecraft.
This pack makes all leaves more "bushier" which adds even more beauty, but along side that, it also adds the new autumn color scheme of the oak leaves that was originally planned for 1.14. The new autumn colors will only be feature in these better tree addons. Also this pack adds the new 3D apple textures that will come naturally in the 1.14 update.