When Mojang changed the texture of lava from the texture used in Classic to the pre-PC 1.5 lava texture in around 0.7.0, they didn't make it so lava would have a notable animation when looked at from a distance (the Classic texture still shows up when doing this). This can be compared with older versions of PC, and you will notice a difference.

Steps to reproduce:

1. If you have PC, downgrade to an older version of Minecraft (using profile editor; versions Beta 1.8 to Release 1.4.7 are recommended for this, for creative mode).
2. Go to the Nether after creating a world in that version. (Going to the Nether is a good way to observe this.)
3. Observe lava animation from a distance (you will notice an animation).
4. Switch to PE.
5. Go to the Nether. Observe lava (you will notice that the animation stops after about 10-20 blocks away from you).

This could be intended (though I highly doubt it) and might be fixed when they update the lava texture to PC's current texture.