Many mechanics, and bugs, and features. Redstone is very different because the bug/exploit parity doesn't exist and even obvious features are different (Redstone attaches to pistons). When they add a new mechanic, the bugs are different and unique to each game. Like because cauldrons can hold potions in bedrock, you can (idk if its changed) use the newish block dripstone to increment the potion fullness, duplicating it.