The grass and water tiles are darker versions of the ones from pack 1. But if you mean you wanna make a seamless transition between entering the cave and leaving without a loading screen, that should be possible with the right script. You could put the top of the cliffside on a layer above the player and have that layer turn transparent once a characters walks through a cave door. It might be easier if you merge the outdoor tiles and cave tiles into one big spritesheet instead of 2 separate ones