Difficulty means nothing to the game

I have an iPad mini 2, not 1.

Difficulty on Easy, Normal and Hard acts all as Hard. The hunger goes fast on Easy like it would on Hard and mobs spawn in little groups no matter what difficulty but peaceful.

What should happen;
Mob spawn amount varies by difficulty.
Hunger decrease rate varies by difficulty.

What does happen;
Mob spawn amount follow rules of easy.
Hunger decrease rate follow rules of hard.

How to reproduce;
Get a stopwatch,
Go on a world on Easy and exhaust yourself by sprinting.
Take note of how long that took.
Now take note of the seed and create a world by the same seed,
Start exhausting yourself on Hard.
Take note of how long that took.
Compare the 2 notes.