I don't take it there are any differences in spawning distances;
(Primarily, the best spawning rates are on PC for more mobs).
As far as having mobs pop up in the area..
can't say for sure but I believe it's from 22 up to about 128 max blocks/meters away judging from Ghast's in the Nether.
I do know mobs can track or shoot you from about 16 blocks away (that's disregarding what the Ghast can do).
Getting all mobs in an area to despawn, you need to be 128 blocks apart: which is how villages don't get attacked until you get there at night.
I don't know it all, but I hope I've shared enough