In Pocket Edition the mobs don't act similar to their PC counterparts.
In PC, hostile mobs are actually a problem: the skeletons have good aim, the zombies and the spiders are fast. However; in PE, even on the highest difficulty I find it to be much easier than Hard on PC.
MCPE-9462
Mob AI Does Not Match PC Difficulty
Resolved
Works As Intended
0
(Unassigned)
Unconfirmed
Tablet - Android - Asus Nexus 7
Android 5.1
0.12.1 Beta 2
Retrieved
Please do not assume the differences between any editions of Minecraft are bugs. If you wish to request new features or tweaks for Minecraft: Pocket Edition, please use the Suggestions Forum or Subreddit.