Minecraft wiki entry for Blocks, associated text: Differences to investigate according to winmerge results (many may just be insignificant compression differences):
Enchanting table bottom texture changed in 18w44a and 18w50a
Acacia, birch, dark oak, jungle and oak trapdoors and the observer back and top changed between 17w47a and 1.13.2 (likely just compression)
List textures which are or were duplicates:
13w43a dark oak log was added named as big oak log, but with spruce logtexture
Whenever birch leaves got a unique texture
Original acacia and dark oak leaves
Melon vs pumpkin stem and their attached versions
Water overlay texture used for water against glass and co. MC-35790 implied a 15w43b introduction, MC-128276 a 18w22b change and 1.16-pre5's changelogs a darkening, but these all need confirmed. 